{
 "instance": {
  "cit-10q_20200331.htm": {
   "axisCustom": 1,
   "axisStandard": 47,
   "contextCount": 731,
   "dts": {
    "calculationLink": {
     "local": [
      "cit-20200331_cal.xml"
     ]
    },
    "definitionLink": {
     "local": [
      "cit-20200331_def.xml"
     ],
     "remote": [
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-eedm-def-2019-01-31.xml",
      "http://xbrl.fasb.org/srt/2019/elts/srt-eedm1-def-2019-01-31.xml"
     ]
    },
    "inline": {
     "local": [
      "cit-10q_20200331.htm"
     ]
    },
    "labelLink": {
     "local": [
      "cit-20200331_lab.xml"
     ],
     "remote": [
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-doc-2019-01-31.xml",
      "https://xbrl.sec.gov/dei/2019/dei-doc-2019-01-31.xml"
     ]
    },
    "presentationLink": {
     "local": [
      "cit-20200331_pre.xml"
     ]
    },
    "referenceLink": {
     "remote": [
      "https://xbrl.sec.gov/dei/2019/dei-ref-2019-01-31.xml",
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-ref-2019-01-31.xml"
     ]
    },
    "schema": {
     "local": [
      "cit-20200331.xsd"
     ],
     "remote": [
      "http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xl-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xlink-2003-12-31.xsd",
      "http://www.xbrl.org/2005/xbrldt-2005.xsd",
      "https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd",
      "http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd",
      "https://xbrl.sec.gov/currency/2019/currency-2019-01-31.xsd",
      "https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd",
      "http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd",
      "https://xbrl.sec.gov/exch/2019/exch-2019-01-31.xsd",
      "http://www.xbrl.org/lrr/arcrole/factExplanatory-2009-12-16.xsd",
      "http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd",
      "http://www.xbrl.org/lrr/role/net-2009-12-16.xsd",
      "https://xbrl.sec.gov/naics/2017/naics-2017-01-31.xsd",
      "https://xbrl.sec.gov/sic/2011/sic-2011-01-31.xsd",
      "http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd",
      "http://www.xbrl.org/2006/ref-2006-02-27.xsd",
      "http://xbrl.fasb.org/srt/2019/elts/srt-types-2019-01-31.xsd",
      "http://xbrl.fasb.org/srt/2019/elts/srt-roles-2019-01-31.xsd",
      "https://xbrl.sec.gov/stpr/2018/stpr-2018-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-roles-2019-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-types-2019-01-31.xsd",
      "http://www.xbrl.org/lrr/role/deprecated-2009-12-16.xsd",
      "http://www.xbrl.org/lrr/role/reference-2009-12-16.xsd",
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-parts-codification-2019-01-31.xsd"
     ]
    }
   },
   "elementCount": 959,
   "entityCount": 1,
   "hidden": {
    "http://fasb.org/us-gaap/2019-01-31": 60,
    "http://www.cit.com/20200331": 10,
    "http://xbrl.sec.gov/dei/2019-01-31": 6,
    "total": 76
   },
   "keyCustom": 136,
   "keyStandard": 501,
   "memberCustom": 61,
   "memberStandard": 92,
   "nsprefix": "cit",
   "nsuri": "http://www.cit.com/20200331",
   "report": {
    "R1": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "dei:DocumentType",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "document",
     "isDefault": "true",
     "longName": "100000 - Document - Document and Entity Information",
     "role": "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation",
     "shortName": "Document and Entity Information",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "dei:DocumentType",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R10": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureAndSignificantAccountingPoliciesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100090 - Disclosure - Business and Summary of Significant Accounting Policies",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPolicies",
     "shortName": "Business and Summary of Significant Accounting Policies",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureAndSignificantAccountingPoliciesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R100": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:MarginDepositAssets",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100990 - Disclosure - Derivative Financial Instruments (Notional Amount and Fair Values of Derivative Financial Instruments) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsParentheticalDetails",
     "shortName": "Derivative Financial Instruments (Notional Amount and Fair Values of Derivative Financial Instruments) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:MarginDepositAssets",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R101": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFairValueHedgingInstrumentsStatementsOfFinancialPerformanceAndFinancialPositionLocationTableTextBlock",
       "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipAxis_us-gaapFairValueHedgingMember_us-gaapFinancialInstrumentAxis_us-gaapDerivativeMember_us-gaapHedgingDesignationAxis_us-gaapDesignatedAsHedgingInstrumentMember_us-gaapIncomeStatementLocationAxis_us-gaapInterestExpenseMember_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:GainLossOnFairValueHedgesRecognizedInEarnings",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101000 - Disclosure - Derivative Financial Instruments (Gains (Losses) of Fair Value Hedges Recognized as Interest Expense) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
     "shortName": "Derivative Financial Instruments (Gains (Losses) of Fair Value Hedges Recognized as Interest Expense) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFairValueHedgingInstrumentsStatementsOfFinancialPerformanceAndFinancialPositionLocationTableTextBlock",
       "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipAxis_us-gaapFairValueHedgingMember_us-gaapFinancialInstrumentAxis_us-gaapDerivativeMember_us-gaapHedgingDesignationAxis_us-gaapDesignatedAsHedgingInstrumentMember_us-gaapIncomeStatementLocationAxis_us-gaapInterestExpenseMember_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:GainLossOnFairValueHedgesRecognizedInEarnings",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R102": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ScheduleOfCumulativeFairValueHedgingAdjustmentsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipAxis_us-gaapFairValueHedgingMember_us-gaapFairValueByMeasurementBasisAxis_us-gaapCarryingReportedAmountFairValueDisclosureMember_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:LongTermDebtFairValue",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101010 - Disclosure - Derivative Financial Instruments (Carrying Value of Hedged Items and Associated Cumulative Hedging Adjustment Relating for Fair Value Hedges) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
     "shortName": "Derivative Financial Instruments (Carrying Value of Hedged Items and Associated Cumulative Hedging Adjustment Relating for Fair Value Hedges) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ScheduleOfCumulativeFairValueHedgingAdjustmentsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipAxis_us-gaapFairValueHedgingMember_us-gaapFairValueByMeasurementBasisAxis_us-gaapEstimateOfFairValueFairValueDisclosureMember_us-gaapHedgingDesignationAxis_us-gaapDesignatedAsHedgingInstrumentMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:LongTermDebtFairValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R103": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ScheduleOfCumulativeFairValueHedgingAdjustmentsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipAxis_us-gaapFairValueHedgingMember_us-gaapFairValueByMeasurementBasisAxis_us-gaapCarryingReportedAmountFairValueDisclosureMember_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:LongTermDebtFairValue",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101020 - Disclosure - Derivative Financial Instruments (Carrying Value of Hedged Items and Associated Cumulative Hedging Adjustment Relating for Fair Value Hedges) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
     "shortName": "Derivative Financial Instruments (Carrying Value of Hedged Items and Associated Cumulative Hedging Adjustment Relating for Fair Value Hedges) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": null
    },
    "R104": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfNetInvestmentHedgesInAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapDerivativeInstrumentRiskAxis_us-gaapForeignExchangeForwardMember_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipAxis_us-gaapNetInvestmentHedgingMember_us-gaapHedgingDesignationAxis_us-gaapDesignatedAsHedgingInstrumentMember_20200101_20200331",
      "decimals": "-6",
      "first": true,
      "lang": null,
      "name": "us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101030 - Disclosure - Derivative Financial Instruments (Pre-tax Net Gains (Losses) Relating to Derivatives Designated as Net Investment Hedges) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails",
     "shortName": "Derivative Financial Instruments (Pre-tax Net Gains (Losses) Relating to Derivatives Designated as Net Investment Hedges) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfNetInvestmentHedgesInAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapDerivativeInstrumentRiskAxis_us-gaapForeignExchangeForwardMember_us-gaapDerivativeInstrumentsGainLossByHedgingRelationshipAxis_us-gaapNetInvestmentHedgingMember_us-gaapHedgingDesignationAxis_us-gaapDesignatedAsHedgingInstrumentMember_20200101_20200331",
      "decimals": "-6",
      "first": true,
      "lang": null,
      "name": "us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R105": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DerivativeGainLossOnDerivativeNet",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101040 - Disclosure - Derivative Financial Instruments (Gains (Losses) of Non-Qualifying Hedges Recognized as Other Non-interest Income) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
     "shortName": "Derivative Financial Instruments (Gains (Losses) of Non-Qualifying Hedges Recognized as Other Non-interest Income) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DerivativeGainLossOnDerivativeNet",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R106": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:InvestmentTableTextBlock",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:AvailableForSaleSecuritiesDebtSecurities",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101050 - Disclosure - Fair Value (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
     "shortName": "Fair Value (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFairValueByMeasurementFrequencyAxis_us-gaapFairValueMeasurementsRecurringMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:AvailableForSaleSecuritiesDebtSecurities",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R107": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFairValueByMeasurementFrequencyAxis_us-gaapFairValueMeasurementsRecurringMember_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:AssetsFairValueDisclosure",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101060 - Disclosure - Fair Value (Quantitative Information about Level 3 Fair Value Measurements-Recurring) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
     "shortName": "Fair Value (Quantitative Information about Level 3 Fair Value Measurements-Recurring) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFairValueByFairValueHierarchyLevelAxis_us-gaapFairValueInputsLevel3Member_us-gaapFairValueByLiabilityClassAxis_us-gaapDerivativeFinancialInstrumentsAssetsMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:AssetsFairValueDisclosure",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R108": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisGainLossIncludedInEarningsTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFairValueByAssetClassAxis_us-gaapAvailableforsaleSecuritiesMember_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101070 - Disclosure - Fair Value (Changes in Estimated Fair Value for Financial Assets and Liabilities Measured on Recurring Basis) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails",
     "shortName": "Fair Value (Changes in Estimated Fair Value for Financial Assets and Liabilities Measured on Recurring Basis) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisGainLossIncludedInEarningsTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFairValueByAssetClassAxis_us-gaapAvailableforsaleSecuritiesMember_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R109": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueByBalanceSheetGroupingTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFairValueByMeasurementBasisAxis_us-gaapCarryingReportedAmountFairValueDisclosureMember_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:AssetsHeldForSaleLongLivedFairValueDisclosure",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101080 - Disclosure - Fair Value (Carrying Value of Assets Measured at Fair Value on a Non-Recurring Basis) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails",
     "shortName": "Fair Value (Carrying Value of Assets Measured at Fair Value on a Non-Recurring Basis) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueAssetsMeasuredOnNonrecurringBasisTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFairValueByMeasurementBasisAxis_us-gaapCarryingReportedAmountFairValueDisclosureMember_us-gaapFairValueByMeasurementFrequencyAxis_us-gaapFairValueMeasurementsNonrecurringMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:AssetsHeldForSaleLongLivedFairValueDisclosure",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R11": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:AcquisitionAndDiscontinuedOperationsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100100 - Disclosure - Acquisition and Discontinued Operations",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperations",
     "shortName": "Acquisition and Discontinued Operations",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:AcquisitionAndDiscontinuedOperationsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R110": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20191001_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:ImpairmentLossOnTaxCreditInvestments",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101090 - Disclosure - Fair Value (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails",
     "shortName": "Fair Value (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20191001_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:ImpairmentLossOnTaxCreditInvestments",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R111": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:InterestBearingDepositsInBanks",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101100 - Disclosure - Fair Value (Carrying and Estimated Fair Values of Financial Instruments) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
     "shortName": "Fair Value (Carrying and Estimated Fair Values of Financial Instruments) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueByBalanceSheetGroupingTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFairValueByMeasurementBasisAxis_us-gaapCarryingReportedAmountFairValueDisclosureMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:InterestBearingDepositsInBanks",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R112": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "cit:AcquisitionAndDiscontinuedOperationsTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_us-gaapEquityInterestIssuedOrIssuableByTypeAxis_us-gaapCommonStockMember_20200101_20200101",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued",
      "reportCount": 1,
      "unitRef": "U_xbrlishares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101110 - Disclosure - Stockholders' Equity (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityNarrativeDetails",
     "shortName": "Stockholders' Equity (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R113": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20191231",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:CommonStockSharesOutstanding",
      "reportCount": 1,
      "unitRef": "U_xbrlishares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101120 - Disclosure - Stockholder's Equity (Schedule of Common Stock Activity) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails",
     "shortName": "Stockholder's Equity (Schedule of Common Stock Activity) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "INF",
      "lang": null,
      "name": "us-gaap:StockIssuedDuringPeriodSharesAcquisitions",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlishares",
      "xsiNil": "false"
     }
    },
    "R114": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:AociBeforeTaxAttributableToParent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101130 - Disclosure - Stockholders' Equity (Components of Accumulated Other Comprehensive Income (Loss) (\"AOCI\")) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails",
     "shortName": "Stockholders' Equity (Components of Accumulated Other Comprehensive Income (Loss) (\"AOCI\")) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:AociBeforeTaxAttributableToParent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R115": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101140 - Disclosure - Stockholders' Equity (Changes in Accumulated Other Comprehensive Income (Loss) by Component) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
     "shortName": "Stockholders' Equity (Changes in Accumulated Other Comprehensive Income (Loss) by Component) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapStatementEquityComponentsAxis_us-gaapAccumulatedTranslationAdjustmentMember_20191231",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R116": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:OtherComprehensiveIncomeLossBeforeTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101150 - Disclosure - Stockholders' Equity (Before- and After-Tax components of OCI) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails",
     "shortName": "Stockholders' Equity (Before- and After-Tax components of OCI) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:OtherComprehensiveIncomeLossBeforeTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R117": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200301_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:TransitionRuleToImplementCurrentExpectedCreditLossesOptionToDelayTerm",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101160 - Disclosure - Regulatory Capital (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails",
     "shortName": "Regulatory Capital (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200301_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:TransitionRuleToImplementCurrentExpectedCreditLossesOptionToDelayTerm",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R118": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:CommonEquityTierOneCapital",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101170 - Disclosure - Regulatory Capital (Tier 1 Capital And Total Capital Components) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails",
     "shortName": "Regulatory Capital (Tier 1 Capital And Total Capital Components) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:CommonEquityTierOneCapital",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R119": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "link:footnote",
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "cit:CommonEquityTier1CapitalRatioMinimumStated",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101180 - Disclosure - Regulatory Capital (Tier 1 Capital And Total Capital Components) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsParentheticalDetails",
     "shortName": "Regulatory Capital (Tier 1 Capital And Total Capital Components) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "link:footnote",
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "cit:CommonEquityTier1CapitalRatioMinimumStated",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     }
    },
    "R12": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100110 - Disclosure - Loans",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoans",
     "shortName": "Loans",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R120": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "3",
      "first": true,
      "lang": null,
      "name": "us-gaap:EffectiveIncomeTaxRateContinuingOperations",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101190 - Disclosure - Income Taxes (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureIncomeTaxesNarrativeDetails",
     "shortName": "Income Taxes (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "3",
      "first": true,
      "lang": null,
      "name": "us-gaap:EffectiveIncomeTaxRateContinuingOperations",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     }
    },
    "R121": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:SummaryOfOffBalanceSheetCreditRelatedCommitmentsAsWellAsPurchaseAndFundingCommitmentsTableTextBlock",
       "us-gaap:CommitmentsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:FinancingAndLeasingAssetsOnCommitmentsCurrent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101200 - Disclosure - Commitments (Summary of Commitments) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails",
     "shortName": "Commitments (Summary of Commitments) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:SummaryOfOffBalanceSheetCreditRelatedCommitmentsAsWellAsPurchaseAndFundingCommitmentsTableTextBlock",
       "us-gaap:CommitmentsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:FinancingAndLeasingAssetsOnCommitmentsCurrent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R122": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:CommitmentsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-6",
      "first": true,
      "lang": null,
      "name": "cit:FinancingCommitmentsToTradeFinanceClientsThatAreCancelableOnlyAfterANoticePeriodAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101210 - Disclosure - Commitments (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails",
     "shortName": "Commitments (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:CommitmentsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-6",
      "first": true,
      "lang": null,
      "name": "cit:FinancingCommitmentsToTradeFinanceClientsThatAreCancelableOnlyAfterANoticePeriodAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R123": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:LossContingencyDisclosures",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:LossContingencyNewClaimsFiledNumber",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_citLawsuit",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101220 - Disclosure - Contingencies (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureContingenciesNarrativeDetails",
     "shortName": "Contingencies (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:LossContingencyDisclosures",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:LossContingencyNewClaimsFiledNumber",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_citLawsuit",
      "xsiNil": "false"
     }
    },
    "R124": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:InterestAndDividendIncomeOperating",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101230 - Disclosure - Business Segment Information (Segment Pre-Tax Income (Loss)) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
     "shortName": "Business Segment Information (Segment Pre-Tax Income (Loss)) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfSegmentReportingInformationBySegmentTextBlock",
       "us-gaap:SegmentReportingDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "cit:InterestBenefitExpenseNet",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R125": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:Goodwill",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101240 - Disclosure - Goodwill And Intangible Assets (Summary of Goodwill) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfGoodwillDetails",
     "shortName": "Goodwill And Intangible Assets (Summary of Goodwill) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfGoodwillTextBlock",
       "us-gaap:GoodwillAndIntangibleAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:GoodwillAcquiredDuringPeriod",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R126": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:Goodwill",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101250 - Disclosure - Goodwill And Intangible Assets (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
     "shortName": "Goodwill And Intangible Assets (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R127": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FiniteLivedIntangibleAssetsGross",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101260 - Disclosure - Goodwill And Intangible Assets (Summary of Intangible Assets) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
     "shortName": "Goodwill And Intangible Assets (Summary of Intangible Assets) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FiniteLivedIntangibleAssetsGross",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R128": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FiniteLivedIntangibleAssetsNet",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "101270 - Disclosure - Goodwill And Intangible Assets (Summary of Intangible Assets Rollforward) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails",
     "shortName": "Goodwill And Intangible Assets (Summary of Intangible Assets Rollforward) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:AmortizationOfIntangibleAssets",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R13": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AllowanceForCreditLossesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100120 - Disclosure - Allowance For Credit Losses",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLosses",
     "shortName": "Allowance For Credit Losses",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AllowanceForCreditLossesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R14": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100130 - Disclosure - Leases",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLeases",
     "shortName": "Leases",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R15": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100140 - Disclosure - Investment Securities",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecurities",
     "shortName": "Investment Securities",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R16": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100150 - Disclosure - Deposits",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDeposits",
     "shortName": "Deposits",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R17": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:VariableInterestEntityDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100160 - Disclosure - Variable Interest Entities",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntities",
     "shortName": "Variable Interest Entities",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:VariableInterestEntityDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R18": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LongTermDebtTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100170 - Disclosure - Borrowings",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowings",
     "shortName": "Borrowings",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LongTermDebtTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R19": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100180 - Disclosure - Derivative Financial Instruments",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstruments",
     "shortName": "Derivative Financial Instruments",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R2": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:CashAndDueFromBanksIncludingRestrictedCash",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100010 - Statement - Condensed Consolidated Balance Sheets (Unaudited)",
     "role": "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
     "shortName": "Condensed Consolidated Balance Sheets (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:NotesReceivableNet",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R20": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100190 - Disclosure - Fair Value",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValue",
     "shortName": "Fair Value",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R21": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100200 - Disclosure - Stockholders' Equity",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquity",
     "shortName": "Stockholders' Equity",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R22": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100210 - Disclosure - Regulatory Capital",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapital",
     "shortName": "Regulatory Capital",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R23": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:IncomeTaxDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100220 - Disclosure - Income Taxes",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureIncomeTaxes",
     "shortName": "Income Taxes",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:IncomeTaxDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R24": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CommitmentsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100230 - Disclosure - Commitments",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitments",
     "shortName": "Commitments",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CommitmentsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R25": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LossContingencyDisclosures",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100240 - Disclosure - Contingencies",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureContingencies",
     "shortName": "Contingencies",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LossContingencyDisclosures",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R26": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SegmentReportingDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100250 - Disclosure - Business Segment Information",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformation",
     "shortName": "Business Segment Information",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SegmentReportingDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R27": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:GoodwillAndIntangibleAssetsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100260 - Disclosure - Goodwill And Intangible Assets",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssets",
     "shortName": "Goodwill And Intangible Assets",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:GoodwillAndIntangibleAssetsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R28": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureAndSignificantAccountingPoliciesTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:BasisOfAccountingPolicyPolicyTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100270 - Disclosure - Business and Summary of Significant Accounting Policies (Policies)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies",
     "shortName": "Business and Summary of Significant Accounting Policies (Policies)",
     "subGroupType": "policies",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureAndSignificantAccountingPoliciesTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:BasisOfAccountingPolicyPolicyTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R29": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100280 - Disclosure - Acquisition and Discontinued Operations (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables",
     "shortName": "Acquisition and Discontinued Operations (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R3": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:RestrictedCashAndDueFromBanks",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100020 - Statement - Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)",
     "role": "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical",
     "shortName": "Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:OtherAssetsFairValueDisclosure",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R30": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:ScheduleOfFinanceReceivablesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100290 - Disclosure - Loans (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables",
     "shortName": "Loans (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:ScheduleOfFinanceReceivablesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R31": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:AllowanceForCreditLossesTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100300 - Disclosure - Allowance For Credit Losses (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesTables",
     "shortName": "Allowance For Credit Losses (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:AllowanceForCreditLossesTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R32": {
     "firstAnchor": {
      "ancestors": [
       "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:SupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100310 - Disclosure - Leases (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesTables",
     "shortName": "Leases (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:SupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R33": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:InvestmentTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100320 - Disclosure - Investment Securities (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesTables",
     "shortName": "Investment Securities (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:InvestmentTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R34": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DepositLiabilitiesTypeTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100330 - Disclosure - Deposits (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsTables",
     "shortName": "Deposits (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DepositLiabilitiesTypeTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R35": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:VariableInterestEntityDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfVariableInterestEntitiesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100340 - Disclosure - Variable Interest Entities (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesTables",
     "shortName": "Variable Interest Entities (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:VariableInterestEntityDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfVariableInterestEntitiesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R36": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:LongTermDebtTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfDebtInstrumentsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100350 - Disclosure - Borrowings (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsTables",
     "shortName": "Borrowings (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:LongTermDebtTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfDebtInstrumentsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R37": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfNotionalAmountsOfOutstandingDerivativePositionsTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100360 - Disclosure - Derivative Financial Instruments (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsTables",
     "shortName": "Derivative Financial Instruments (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfNotionalAmountsOfOutstandingDerivativePositionsTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R38": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100370 - Disclosure - Fair Value (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueTables",
     "shortName": "Fair Value (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R39": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfCommonStockOutstandingRollForwardTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100380 - Disclosure - Stockholders' Equity (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityTables",
     "shortName": "Stockholders' Equity (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfCommonStockOutstandingRollForwardTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R4": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:InterestAndFeeIncomeLoansAndLeases",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100030 - Statement - Condensed Consolidated Statements of Income (Unaudited)",
     "role": "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited",
     "shortName": "Condensed Consolidated Statements of Income (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:InterestAndFeeIncomeLoansAndLeases",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R40": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100390 - Disclosure - Regulatory Capital (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTables",
     "shortName": "Regulatory Capital (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R41": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:CommitmentsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:SummaryOfOffBalanceSheetCreditRelatedCommitmentsAsWellAsPurchaseAndFundingCommitmentsTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100400 - Disclosure - Commitments (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsTables",
     "shortName": "Commitments (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:CommitmentsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:SummaryOfOffBalanceSheetCreditRelatedCommitmentsAsWellAsPurchaseAndFundingCommitmentsTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R42": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:SegmentReportingDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfSegmentReportingInformationBySegmentTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100410 - Disclosure - Business Segment Information (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationTables",
     "shortName": "Business Segment Information (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:SegmentReportingDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfSegmentReportingInformationBySegmentTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R43": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:GoodwillAndIntangibleAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfGoodwillTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100420 - Disclosure - Goodwill And Intangible Assets (Tables)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsTables",
     "shortName": "Goodwill And Intangible Assets (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:GoodwillAndIntangibleAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfGoodwillTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R44": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:LoansAndLeasesReceivablePastDueStatusPolicy",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:LoansandLeasesReceivableNonperformingPeriodPastDue",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100430 - Disclosure - Business and Summary of Significant Accounting Policies (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
     "shortName": "Business and Summary of Significant Accounting Policies (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:LoansAndLeasesReceivablePastDueStatusPolicy",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "cit:LoansandLeasesReceivableNonperformingPeriodPastDue",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R45": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:Goodwill",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100440 - Disclosure - Acquisition and Discontinued Operations (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
     "shortName": "Acquisition and Discontinued Operations (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity",
       "p",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapDisposalGroupClassificationAxis_us-gaapSegmentDiscontinuedOperationsMember_20200101_20200331",
      "decimals": "INF",
      "lang": null,
      "name": "us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R46": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:Goodwill",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100450 - Disclosure - Acquisition and Discontinued Operations (Consideration and Net Assets Acquired) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
     "shortName": "Acquisition and Discontinued Operations (Consideration and Net Assets Acquired) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_20200101",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R47": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_20200101",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:BusinessCombinationUnpaidPrincipalBalance",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100460 - Disclosure - Acquisition and Discontinued Operations (Summary of Loan Valuations by Division in Each Segment) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
     "shortName": "Acquisition and Discontinued Operations (Summary of Loan Valuations by Division in Each Segment) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_20200101",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:BusinessCombinationUnpaidPrincipalBalance",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R48": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:SummaryOfKeyValuationInputAssumptionsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_srtRangeAxis_srtWeightedAverageMember_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_us-gaapMeasurementInputTypeAxis_us-gaapMeasurementInputDiscountRateMember_us-gaapStatementBusinessSegmentsAxis_citCommercialBankingBusinessSegmentMember_us-gaapSubsegmentsAxis_citCommercialFinanceMember_20200101",
      "decimals": "2",
      "first": true,
      "lang": null,
      "name": "us-gaap:LoansHeldForSaleMeasurementInput",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100470 - Disclosure - Acquisition and Discontinued Operations (Summary of Key Valuation Input Assumptions by Division) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
     "shortName": "Acquisition and Discontinued Operations (Summary of Key Valuation Input Assumptions by Division) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:SummaryOfKeyValuationInputAssumptionsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_srtRangeAxis_srtWeightedAverageMember_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_us-gaapMeasurementInputTypeAxis_us-gaapMeasurementInputDiscountRateMember_us-gaapStatementBusinessSegmentsAxis_citCommercialBankingBusinessSegmentMember_us-gaapSubsegmentsAxis_citCommercialFinanceMember_20200101",
      "decimals": "2",
      "first": true,
      "lang": null,
      "name": "us-gaap:LoansHeldForSaleMeasurementInput",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     }
    },
    "R49": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinitelivedIntangibleAssetsAcquired1",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100480 - Disclosure - Acquisition and Discontinued Operations (Summary of Intangible Assets Recorded in Conjunction with MOB Transaction ) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
     "shortName": "Acquisition and Discontinued Operations (Summary of Intangible Assets Recorded in Conjunction with MOB Transaction ) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis_us-gaapCoreDepositsMember_20200101_20200101",
      "decimals": null,
      "lang": "en-US",
      "name": "us-gaap:FiniteLivedIntangibleAssetsAmortizationMethod",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R5": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:NetIncomeLoss",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100040 - Statement - Condensed Consolidated Statements of Comprehensive Income (Unaudited)",
     "role": "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited",
     "shortName": "Condensed Consolidated Statements of Comprehensive Income (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R50": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:BusinessAcquisitionProFormaInformationTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:BusinessAcquisitionsProFormaInterestIncome",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100490 - Disclosure - Acquisition and Discontinued Operations (Selected Unaudited Pro Forma Financial Information) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSelectedUnauditedProFormaFinancialInformationDetails",
     "shortName": "Acquisition and Discontinued Operations (Selected Unaudited Pro Forma Financial Information) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:BusinessAcquisitionProFormaInformationTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBusinessAcquisitionAxis_citMutualOfOmahaBankMember_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:BusinessAcquisitionsProFormaInterestIncome",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R51": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100500 - Disclosure - Loans (Schedule of Loans by Product) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails",
     "shortName": "Loans (Schedule of Loans by Product) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ScheduleOfFinanceReceivablesTableTextBlock",
       "us-gaap:LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapAccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_us-gaapLoansReceivableMember_us-gaapFinancingReceivablePortfolioSegmentAxis_us-gaapCommercialPortfolioSegmentMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R52": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100510 - Disclosure - Loans (Schedule of Loans by Segment, Based on Obligor Location) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails",
     "shortName": "Loans (Schedule of Loans by Segment, Based on Obligor Location) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ScheduleOfSegmentLoansAndLeasesHeldForInvestmentBasedOnObligorLocationTableTextBlock",
       "us-gaap:LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapGeographicDistributionAxis_us-gaapGeographicDistributionDomesticMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R53": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ComponentsOfNetInvestmentInFinanceReceivablesTableTextBlock",
       "us-gaap:LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:UnearnedIncome",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100520 - Disclosure - Loans (Components of Net Investment) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansComponentsOfNetInvestmentDetails",
     "shortName": "Loans (Components of Net Investment) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ComponentsOfNetInvestmentInFinanceReceivablesTableTextBlock",
       "us-gaap:LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:UnearnedIncome",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R54": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100530 - Disclosure - Loans (Commercial Loans - By Risk Rating) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
     "shortName": "Loans (Commercial Loans - By Risk Rating) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFinancingReceivablePortfolioSegmentAxis_us-gaapCommercialPortfolioSegmentMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FinancingReceivableOriginatedInCurrentFiscalYear",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R55": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100540 - Disclosure - Loans (Commercial Loans - By Risk Rating) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
     "shortName": "Loans (Commercial Loans - By Risk Rating) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapCreditLossStatusAxis_us-gaapFinancialAssetAcquiredWithCreditDeteriorationMember_us-gaapFinancingReceivablePortfolioSegmentAxis_us-gaapCommercialPortfolioSegmentMember_us-gaapFinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_citRealEstateFinanceMember_us-gaapInternalCreditAssessmentAxis_us-gaapCriticizedMember_20191231",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R56": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "2",
      "first": true,
      "lang": null,
      "name": "cit:AverageLoansToValuePercentage",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100550 - Disclosure - Loans (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails",
     "shortName": "Loans (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "2",
      "first": true,
      "lang": null,
      "name": "cit:AverageLoansToValuePercentage",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     }
    },
    "R57": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100560 - Disclosure - Loans (Schedule of Consumer Loans LTV Distributions) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
     "shortName": "Loans (Schedule of Consumer Loans LTV Distributions) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFinancingReceivablePortfolioSegmentAxis_us-gaapConsumerPortfolioSegmentMember_us-gaapLoanToValueAxis_citLtvGreaterThan125PercentMember_20191231",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R58": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBalanceSheetLocationAxis_us-gaapOtherAssetsMember_us-gaapFinancingReceivablePortfolioSegmentAxis_us-gaapConsumerPortfolioSegmentMember_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:InterestReceivable",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100570 - Disclosure - Loans (Schedule of Consumer Loans LTV Distributions) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsParentheticalDetails",
     "shortName": "Loans (Schedule of Consumer Loans LTV Distributions) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": null
    },
    "R59": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100580 - Disclosure - Loans (Schedule of Consumer Loans Current FICO Score Distributions) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
     "shortName": "Loans (Schedule of Consumer Loans Current FICO Score Distributions) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFinancingReceivablePortfolioSegmentAxis_us-gaapConsumerPortfolioSegmentMember_us-gaapStatementBusinessSegmentsAxis_citConsumerBankingBusinessSegmentMember_20191231",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R6": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20181231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:StockholdersEquity",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100050 - Statement - Condensed Consolidated Statements of Stockholders' Equity (Unaudited)",
     "role": "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited",
     "shortName": "Condensed Consolidated Statements of Stockholders' Equity (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20181231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:StockholdersEquity",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R60": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapBalanceSheetLocationAxis_us-gaapOtherAssetsMember_us-gaapFinancingReceivablePortfolioSegmentAxis_us-gaapConsumerPortfolioSegmentMember_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:InterestReceivable",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100590 - Disclosure - Loans (Schedule of Consumer Loans Current FICO Score Distributions) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsParentheticalDetails",
     "shortName": "Loans (Schedule of Consumer Loans Current FICO Score Distributions) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": null
    },
    "R61": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:PastDueFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableRecordedInvestmentPastDue",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100600 - Disclosure - Loans (Loans - Delinquency Status) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
     "shortName": "Loans (Loans - Delinquency Status) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:PastDueFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FinancingReceivableRecordedInvestmentCurrent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R62": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100610 - Disclosure - Loans (Loans - Delinquency Status) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
     "shortName": "Loans (Loans - Delinquency Status) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:PastDueFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapCreditLossStatusAxis_citPurchasedCreditDeterioratedLoansMember_20200331",
      "decimals": "-8",
      "lang": null,
      "name": "us-gaap:FinancingReceivableAfterDeferredIncomeOffset",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R63": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFinancingReceivablesNonAccrualStatusTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableRecordedInvestmentNonaccrualStatus",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100620 - Disclosure - Loans (Loans on Non-accrual Status) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
     "shortName": "Loans (Loans on Non-accrual Status) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFinancingReceivablesNonAccrualStatusTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:ForeclosedAssets",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R64": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFinancingReceivablesNonAccrualStatusTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableNonaccrualInterestIncome",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100630 - Disclosure - Loans (Loans on Non-accrual Status) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails",
     "shortName": "Loans (Loans on Non-accrual Status) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFinancingReceivablesNonAccrualStatusTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableNonaccrualInterestIncome",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R65": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ScheduleOfLoansInProcessOfForeclosureTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:MortgageLoansInProcessOfForeclosureAmount",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100640 - Disclosure - Loans (Schedule of Loans In Process of Foreclosure) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansInProcessOfForeclosureDetails",
     "shortName": "Loans (Schedule of Loans In Process of Foreclosure) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R66": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ScheduleOfLoansInProcessOfForeclosureTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:MortgageLoansInProcessOfForeclosureAmount",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100650 - Disclosure - Loans (Schedule of Loans In Process of Foreclosure) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansInProcessOfForeclosureParentheticalDetails",
     "shortName": "Loans (Schedule of Loans In Process of Foreclosure) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "cit:ScheduleOfLoansInProcessOfForeclosureTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapCreditLossStatusAxis_us-gaapFinancialAssetAcquiredWithCreditDeteriorationMember_20191231",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:MortgageLoansInProcessOfForeclosureAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R67": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:ImpairedFinancingReceivableRelatedAllowance",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100660 - Disclosure - Loans (Impaired Loans) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
     "shortName": "Loans (Impaired Loans) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20190101_20191231",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:ImpairedFinancingReceivableAverageRecordedInvestment",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R68": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20190101_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:ImpairedFinancingReceivableInterestIncome",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100670 - Disclosure - Loans (Impaired Loans) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansParentheticalDetails",
     "shortName": "Loans (Impaired Loans) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20190101_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:ImpairedFinancingReceivableInterestIncome",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R69": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:PurchasedCreditImpairedLoansWithDeterioratedCreditQualityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapCreditLossStatusAxis_us-gaapFinancialAssetAcquiredWithCreditDeteriorationMember_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivablePurchasedWithCreditDeteriorationAmountAtParValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100680 - Disclosure - Loans (PCD Loans) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
     "shortName": "Loans (PCD Loans) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:PurchasedCreditImpairedLoansWithDeterioratedCreditQualityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapCreditLossStatusAxis_us-gaapFinancialAssetAcquiredWithCreditDeteriorationMember_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivablePurchasedWithCreditDeteriorationAmountAtParValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R7": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:CommonStockDividendsPerShareCashPaid",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD_xbrlishares",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100060 - Statement - Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (Parenthetical)",
     "role": "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical",
     "shortName": "Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (Parenthetical)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:CommonStockDividendsPerShareCashPaid",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD_xbrlishares",
      "xsiNil": "false"
     }
    },
    "R70": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock",
       "us-gaap:AllowanceForCreditLossesTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableAllowanceForCreditLossesWriteOffs",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100690 - Disclosure - Loans (PCD Loans) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansParentheticalDetails",
     "shortName": "Loans (PCD Loans) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:PurchasedCreditImpairedLoansWithDeterioratedCreditQualityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapCreditLossStatusAxis_us-gaapFinancialAssetAcquiredWithCreditDeteriorationMember_20200101_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R71": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:ImpairedFinancingReceivableRecordedInvestment",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100700 - Disclosure - Loans (PCI Loans) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
     "shortName": "Loans (PCI Loans) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R72": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20181231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100710 - Disclosure - Loans (Schedule of Changes to the Accretable Yield for PCI Loans) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfChangesToAccretableYieldForPCILoansDetails",
     "shortName": "Loans (Schedule of Changes to the Accretable Yield for PCI Loans) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20181231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R73": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:TroubledDebtRestructuringsOnFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableModificationsRecordedInvestment",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100720 - Disclosure - Loans (Summary of Recorded Investments of TDRs (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfTdrsDetails",
     "shortName": "Loans (Summary of Recorded Investments of TDRs (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:TroubledDebtRestructuringsOnFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableModificationsRecordedInvestment",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R74": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:TroubledDebtRestructuringsOnFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFinancialInstrumentAxis_us-gaapCommercialLoanMember_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:RecordedInvestmentTroubledDebtRestructuringRelatedToModifications",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100730 - Disclosure - Loans (Summary of Recorded Investments of Modifications) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfModificationsDetails",
     "shortName": "Loans (Summary of Recorded Investments of Modifications) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:TroubledDebtRestructuringsOnFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFinancialInstrumentAxis_us-gaapCommercialLoanMember_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:RecordedInvestmentTroubledDebtRestructuringRelatedToModifications",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R75": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FinancingReceivableAllowanceForCreditLosses",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100740 - Disclosure - Allowance For Credit Losses (Schedule of Allowance for Credit Losses and Recorded Investment in Finance Receivables) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
     "shortName": "Allowance For Credit Losses (Schedule of Allowance for Credit Losses and Recorded Investment in Finance Receivables) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock",
       "us-gaap:AllowanceForCreditLossesTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20181231",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FinancingReceivableAllowanceForCreditLosses",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R76": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock",
       "us-gaap:AllowanceForCreditLossesTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200101",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:AllowanceForCreditLossesRecognizedOnPCDAssets",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100750 - Disclosure - Allowance For Credit Losses (Schedule of Allowance for Credit Losses and Recorded Investment in Finance Receivables) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesParentheticalDetails",
     "shortName": "Allowance For Credit Losses (Schedule of Allowance for Credit Losses and Recorded Investment in Finance Receivables) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock",
       "us-gaap:AllowanceForCreditLossesTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:OffBalanceSheetCreditLossLiability",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R77": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:ProvisionForLoanLossesExpensed",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100760 - Disclosure - Allowance For Credit Losses (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesNarrativeDetails",
     "shortName": "Allowance For Credit Losses (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R78": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_srtRangeAxis_srtMaximumMember_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeaseTermOfContract",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100770 - Disclosure - Leases (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesNarrativeDetails",
     "shortName": "Leases (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_srtRangeAxis_srtMaximumMember_20200331",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeaseTermOfContract",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R79": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:SupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesTableTextBlock",
       "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:OperatingLeaseRightOfUseAsset",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100780 - Disclosure - Leases (Schedule of Supplemental Balance Sheet and Cash Flow Information Related to Leases) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfSupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesDetails",
     "shortName": "Leases (Schedule of Supplemental Balance Sheet and Cash Flow Information Related to Leases) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:SupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesTableTextBlock",
       "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:OperatingLeaseRightOfUseAsset",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R8": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:NetIncomeLoss",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100070 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)",
     "role": "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited",
     "shortName": "Condensed Consolidated Statements of Cash Flows (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:Depreciation",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R80": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:LessorLeaseIncomeTableTextBlock",
       "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:OperatingLeaseLeaseIncomeLeasePayments",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100790 - Disclosure - Leases (Schedule of Lease Income Related to Company's Operating and Finance Leases) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails",
     "shortName": "Leases (Schedule of Lease Income Related to Company's Operating and Finance Leases) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:LessorLeaseIncomeTableTextBlock",
       "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:OperatingLeaseLeaseIncomeLeasePayments",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R81": {
     "firstAnchor": {
      "ancestors": [
       "link:footnote",
       "p",
       "cit:LessorLeaseIncomeTableTextBlock",
       "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "cit:LessorLeasedEquipmentPropertyTaxReimbursementsDueFromCustomers",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100800 - Disclosure - Leases (Schedule of Lease Income Related to Company's Operating and Finance Leases) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesParentheticalDetails",
     "shortName": "Leases (Schedule of Lease Income Related to Company's Operating and Finance Leases) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "link:footnote",
       "p",
       "cit:LessorLeaseIncomeTableTextBlock",
       "cit:LeasesOfLesseeAndLessorDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "cit:LessorLeasedEquipmentPropertyTaxReimbursementsDueFromCustomers",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R82": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:InvestmentTableTextBlock",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:AvailableForSaleSecuritiesDebtSecurities",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100810 - Disclosure - Investment Securities (Schedule of Carrying Value of Investment Securities) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesDetails",
     "shortName": "Investment Securities (Schedule of Carrying Value of Investment Securities) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:InvestmentTableTextBlock",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapInvestmentTypeAxis_citNonMarketableSecuritiesMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:Investments",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R83": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:InvestmentTableTextBlock",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FederalHomeLoanBankStockAndFederalReserveBankStock",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100820 - Disclosure - Investment Securities (Schedule of Carrying Value of Investment Securities) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesParentheticalDetails",
     "shortName": "Investment Securities (Schedule of Carrying Value of Investment Securities) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:InvestmentTableTextBlock",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FederalHomeLoanBankStockAndFederalReserveBankStock",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R84": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DebtSecuritiesAvailableForSaleRealizedGainLossExcludingOtherThanTemporaryImpairment",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100830 - Disclosure - Investment Securities (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesNarrativeDetails",
     "shortName": "Investment Securities (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DebtSecuritiesAvailableForSaleRealizedGainLossExcludingOtherThanTemporaryImpairment",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R85": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:InvestmentIncomeTextBlock",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:InterestIncomeDebtSecuritiesAvailableForSaleOperating",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100840 - Disclosure - Investment Securities (Schedule of Interest and Dividend Income) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfInterestAndDividendIncomeDetails",
     "shortName": "Investment Securities (Schedule of Interest and Dividend Income) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:InvestmentIncomeTextBlock",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200101_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:InterestIncomeDebtSecuritiesAvailableForSaleOperating",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R86": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:DebtSecuritiesAvailableForSaleTableTextBlock",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100850 - Disclosure - Investment Securities (Amortized Cost and Fair Value of AFS and HTM Securities) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
     "shortName": "Investment Securities (Amortized Cost and Fair Value of AFS and HTM Securities) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:DebtSecuritiesAvailableForSaleTableTextBlock",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R87": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:DebtSecuritiesAvailableForSaleTableTextBlock",
       "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100860 - Disclosure - Investment Securities (Schedule of Amortized Cost and Fair Value Maturities with Changes Recorded in Net Income) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails",
     "shortName": "Investment Securities (Schedule of Amortized Cost and Fair Value Maturities with Changes Recorded in Net Income) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:InvestmentsClassifiedByContractualMaturityDateTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "4",
      "lang": null,
      "name": "cit:AvailableForSaleDebtSecuritiesAverageYield",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     }
    },
    "R88": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100870 - Disclosure - Investment Securities (Schedule of AFS and HTM - Estimated Unrealized Losses) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails",
     "shortName": "Investment Securities (Schedule of AFS and HTM - Estimated Unrealized Losses) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R89": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:DepositLiabilitiesTypeTableTextBlock",
       "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:InterestBearingDepositLiabilities",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100880 - Disclosure - Deposits (Schedule of Detail on Deposit Types) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfDetailOnDepositTypesDetails",
     "shortName": "Deposits (Schedule of Detail on Deposit Types) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:DepositLiabilitiesTypeTableTextBlock",
       "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:InterestBearingDepositLiabilities",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R9": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "cit:CashAndDueFromBanksIncludingRestrictedCash",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100080 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical)",
     "role": "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnauditedParenthetical",
     "shortName": "Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20190331",
      "decimals": "-5",
      "lang": null,
      "name": "cit:CashAndDueFromBanksIncludingRestrictedCash",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R90": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:TimeDepositMaturitiesTableTextBlock",
       "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:TimeDepositMaturitiesYearOne",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100890 - Disclosure - Deposits (Schedule of Maturities of Time Deposits) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails",
     "shortName": "Deposits (Schedule of Maturities of Time Deposits) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:TimeDepositMaturitiesTableTextBlock",
       "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:TimeDepositMaturitiesYearOne",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R91": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ScheduleOfContractualMaturitiesOfTimeDeposits100000OrMoreTableTextBlock",
       "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:ContractualMaturitiesTimeDeposits100000OrMoreThreeMonthsOrLess",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100900 - Disclosure - Deposits (Schedule of Certificates of Deposit $100 Thousand or More) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails",
     "shortName": "Deposits (Schedule of Certificates of Deposit $100 Thousand or More) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "cit:ScheduleOfContractualMaturitiesOfTimeDeposits100000OrMoreTableTextBlock",
       "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:ContractualMaturitiesTimeDeposits100000OrMoreThreeMonthsOrLess",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R92": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:TimeDepositsAtOrAboveFDICInsuranceLimit",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100910 - Disclosure - Deposits (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsNarrativeDetails",
     "shortName": "Deposits (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:DepositLiabilitiesDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:TimeDepositsAtOrAboveFDICInsuranceLimit",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R93": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:VariableInterestEntityDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "cit:NumberOfConsolidatedVariableInterestEntities",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_citEntity",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100920 - Disclosure - Variable Interest Entities (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesNarrativeDetails",
     "shortName": "Variable Interest Entities (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:VariableInterestEntityDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "cit:NumberOfConsolidatedVariableInterestEntities",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_citEntity",
      "xsiNil": "false"
     }
    },
    "R94": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "us-gaap:VariableInterestEntityDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFinancialInstrumentAxis_citPartnershipInvestmentMember_us-gaapVariableInterestEntitiesByClassificationOfEntityAxis_citUnconsolidatedVariableInterestEntitiesViesMember_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:VariableInterestEntityNonconsolidatedCarryingAmountAssets",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100930 - Disclosure - Variable Interest Entities (Assets and Liabilities in Unconsolidated VIEs) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails",
     "shortName": "Variable Interest Entities (Assets and Liabilities in Unconsolidated VIEs) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "us-gaap:VariableInterestEntityDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFinancialInstrumentAxis_citPartnershipInvestmentMember_us-gaapVariableInterestEntitiesByClassificationOfEntityAxis_citUnconsolidatedVariableInterestEntitiesViesMember_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:VariableInterestEntityNonconsolidatedCarryingAmountAssets",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R95": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:LongTermDebt",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100940 - Disclosure - Borrowings (Schedule of Long-Term Borrowings) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails",
     "shortName": "Borrowings (Schedule of Long-Term Borrowings) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfDebtInstrumentsTextBlock",
       "us-gaap:LongTermDebtTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_srtConsolidatedEntitiesAxis_srtParentCompanyMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:LongTermDebt",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R96": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "us-gaap:RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets",
      "reportCount": 1,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100950 - Disclosure - Borrowings (Narrative) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
     "shortName": "Borrowings (Narrative) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-8",
      "lang": null,
      "name": "cit:PledgedAssets",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R97": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFederalHomeLoanBankAdvancesByBranchOfFHLBBankTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100960 - Disclosure - Borrowings (Schedule of FHLB Balances) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails",
     "shortName": "Borrowings (Schedule of FHLB Balances) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFederalHomeLoanBankAdvancesByBranchOfFHLBBankTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFinancialInstrumentAxis_citLendingAssetsMember_20200331",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R98": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfFederalHomeLoanBankAdvancesByBranchOfFHLBBankTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_us-gaapFinancialInstrumentAxis_citHighQualityLiquidSecuritiesMember_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100970 - Disclosure - Borrowings (Schedule of FHLB Balances) (Parenthetical) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesParentheticalDetails",
     "shortName": "Borrowings (Schedule of FHLB Balances) (Parenthetical) (Details)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": null
    },
    "R99": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DerivativeNotionalAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100980 - Disclosure - Derivative Financial Instruments (Notional Amount and Fair Values of Derivative Financial Instruments) (Details)",
     "role": "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails",
     "shortName": "Derivative Financial Instruments (Notional Amount and Fair Values of Derivative Financial Instruments) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "cit-10q_20200331.htm",
      "contextRef": "C_0001171825_20200331",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DerivativeNotionalAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    }
   },
   "segmentCount": 161,
   "tag": {
    "cit_AccumulatedOtherComprehensiveIncomeActivityBeforeReclassificationMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "AOCI activity before reclassification.",
        "label": "Accumulated Other Comprehensive Income Activity Before Reclassification [Member]",
        "terseLabel": "AOCI activity before reclassification"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeActivityBeforeReclassificationMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_AcquisitionAndDiscontinuedOperationsTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Acquisition and discontinued operations.",
        "label": "Acquisition And Discontinued Operations [Text Block]",
        "terseLabel": "ACQUISITION AND DISCONTINUED OPERATIONS"
       }
      }
     },
     "localname": "AcquisitionAndDiscontinuedOperationsTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperations"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_AcquisitionPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Acquisition.",
        "label": "Acquisition Policy [Text Block]",
        "terseLabel": "Acquisition"
       }
      }
     },
     "localname": "AcquisitionPolicyTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_AllowanceForCreditLossesRecognizedOnPCDAssets": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Allowance for credit losses recognized on PCD assets.",
        "label": "Allowance For Credit Losses Recognized On P C D Assets",
        "terseLabel": "The initial ACL recognized on PCD assets"
       }
      }
     },
     "localname": "AllowanceForCreditLossesRecognizedOnPCDAssets",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_AvailableForSaleDebtSecuritiesAverageYield": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Available-for-sale Debt Securities, Average Yield",
        "label": "Available For Sale Debt Securities Average Yield",
        "terseLabel": "Weighted Average Yield"
       }
      }
     },
     "localname": "AvailableForSaleDebtSecuritiesAverageYield",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAverageYield": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Available for sale securities debt maturities after five through ten years average yield.",
        "label": "Available For Sale Securities Debt Maturities After Five Through Ten Years Average Yield",
        "terseLabel": "After 5 through 10 years, Weighted Average Yield"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAverageYield",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAverageYield": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Available for sale securities debt maturities after one through five years average yield.",
        "label": "Available For Sale Securities Debt Maturities After One Through Five Years Average Yield",
        "terseLabel": "After 1 through 5 years, Weighted Average Yield"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAverageYield",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAverageYield": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Available-for-sale Securities, Debt Maturities, after Ten Years, Average Yield",
        "label": "Available For Sale Securities Debt Maturities After Ten Years Average Yield",
        "terseLabel": "Due after 10 years, Weighted Average Yield"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAverageYield",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAverageYield": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Available for sale securities debt maturities within one year average yield.",
        "label": "Available For Sale Securities Debt Maturities Within One Year Average Yield",
        "terseLabel": "Due in 1 year or less, Weighted Average Yield"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAverageYield",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_AverageFICOScore": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Average FICO score.",
        "label": "Average F I C O Score",
        "terseLabel": "Average FICO score"
       }
      }
     },
     "localname": "AverageFICOScore",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "cit_AverageLoansToValuePercentage": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Average loans to value percentage.",
        "label": "Average Loans To Value Percentage",
        "terseLabel": "Average Loans to Value Percentage"
       }
      }
     },
     "localname": "AverageLoansToValuePercentage",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_BeforeReclassificationOfAccumulatedOtherComprehensiveIncomeAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Before reclassification of accumulated other comprehensive income.",
        "label": "Before Reclassification Of Accumulated Other Comprehensive Income [Axis]",
        "terseLabel": "Before Reclassification Of Accumulated Other Comprehensive Income"
       }
      }
     },
     "localname": "BeforeReclassificationOfAccumulatedOtherComprehensiveIncomeAxis",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_BeforeReclassificationOfAccumulatedOtherComprehensiveIncomeDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Before reclassification of accumulated other comprehensive income.",
        "label": "Before Reclassification Of Accumulated Other Comprehensive Income [Domain]",
        "terseLabel": "Before Reclassification Of Accumulated Other Comprehensive Income"
       }
      }
     },
     "localname": "BeforeReclassificationOfAccumulatedOtherComprehensiveIncomeDomain",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_BusinessAcquisitionsProFormaInterestIncome": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business acquisitions pro forma interest income.",
        "label": "Business Acquisitions Pro Forma Interest Income",
        "terseLabel": "Interest income"
       }
      }
     },
     "localname": "BusinessAcquisitionsProFormaInterestIncome",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSelectedUnauditedProFormaFinancialInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessAcquisitionsProFormaNoninterestIncome": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business acquisitions pro forma noninterest income.",
        "label": "Business Acquisitions Pro Forma Noninterest Income",
        "terseLabel": "Non-interest income"
       }
      }
     },
     "localname": "BusinessAcquisitionsProFormaNoninterestIncome",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSelectedUnauditedProFormaFinancialInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessCapitalMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business capital.",
        "label": "Business Capital [Member]",
        "terseLabel": "Business Capital"
       }
      }
     },
     "localname": "BusinessCapitalMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCertificateOfDepositsWithMaturity": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business combination recognized identifiable assets acquired and liabilities assumed, certificate of deposits with maturity.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Certificate Of Deposits With Maturity",
        "terseLabel": "Certificate of deposits with maturity"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCertificateOfDepositsWithMaturity",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCertificateOfDepositsWithoutMaturity": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business combination recognized identifiable assets acquired and liabilities assumed, certificate of deposits without maturity.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Certificate Of Deposits Without Maturity",
        "terseLabel": "Certificate of deposits without maturity"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCertificateOfDepositsWithoutMaturity",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeposits": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business combination recognized identifiable assets acquired and liabilities assumed deposits.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Deposits",
        "terseLabel": "Deposits"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeposits",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedEquityInvestments": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business combination recognized identifiable assets acquired and liabilities assumed equity investments.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Equity Investments",
        "terseLabel": "Equity investments"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedEquityInvestments",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedMortgageServicingRights": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business combination recognized identifiable assets acquired and liabilities assumed mortgage servicing rights.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Mortgage Servicing Rights",
        "terseLabel": "Mortgage Servicing Rights"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedMortgageServicingRights",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssets": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business combination recognized identifiable assets acquired and liabilities assumed other assets.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Other Assets",
        "terseLabel": "Other assets"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssets",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRightOfUseAssets": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business combination recognized identifiable assets acquired and liabilities assumed right of use assets.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Right Of Use Assets",
        "terseLabel": "Right of use assets"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRightOfUseAssets",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedSecuritiesSoldUnderAgreementsToRepurchase": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": 10040.0,
       "parentTag": "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business combination recognized identifiable assets acquired and liabilities assumed securities sold under agreements to repurchase.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Securities Sold Under Agreements To Repurchase",
        "terseLabel": "Securities sold under agreements to repurchase"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedSecuritiesSoldUnderAgreementsToRepurchase",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedTechnologyAssets": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business combination recognized identifiable assets acquired and liabilities assumed technology assets.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Technology Assets",
        "terseLabel": "Technology assets"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedTechnologyAssets",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_BusinessCombinationUnpaidPrincipalBalance": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Business combination unpaid principal balance.",
        "label": "Business Combination Unpaid Principal Balance",
        "terseLabel": "Total loans, unpaid principal balance"
       }
      }
     },
     "localname": "BusinessCombinationUnpaidPrincipalBalance",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_CITBankMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "CIT bank.",
        "label": "C I T Bank [Member]",
        "terseLabel": "CIT Bank, N.A."
       }
      }
     },
     "localname": "CITBankMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_CapitalConservationBufferRate": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Capital conservation buffer rate.",
        "label": "Capital Conservation Buffer Rate",
        "terseLabel": "Capital conservation buffer rate"
       }
      }
     },
     "localname": "CapitalConservationBufferRate",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsParentheticalDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_CashAndDueFromBanksIncludingRestrictedCash": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10140.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnauditedParenthetical": {
       "order": 10010.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "For banks and other depository institutions: Includes cash on hand (currency and coin), restricted cash, cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.",
        "label": "Cash And Due From Banks Including Restricted Cash",
        "terseLabel": "Cash and due from banks, including restricted balances of $29.6 at March 31, 2020 and $875.2 at December 31, 2019 (see Note 9 for amounts pledged)",
        "verboseLabel": "Cash and due from banks, including restricted balances of $29.6 and $22.9 at March 31, 2020 and 2019, respectively"
       }
      }
     },
     "localname": "CashAndDueFromBanksIncludingRestrictedCash",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnauditedParenthetical"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_CertainLoansAcquiredInTransferAccretableYieldOnPurchasedCreditImpairedLoans": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Certain loans acquired in transfer accretable yield on purchased credit impaired loans.",
        "label": "Certain Loans Acquired In Transfer Accretable Yield On Purchased Credit Impaired Loans",
        "negatedLabel": "Accretable yield on PCI loans"
       }
      }
     },
     "localname": "CertainLoansAcquiredInTransferAccretableYieldOnPurchasedCreditImpairedLoans",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansComponentsOfNetInvestmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableDiscountMovementScheduleRollForwardTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Certain loans acquired in transfer not accounted for as debt securities accretable discount movement schedule roll forward.",
        "label": "Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Discount Movement Schedule Roll Forward Table [Text Block]",
        "terseLabel": "Schedule Of Changes To The Accretable Yield For PCI Loans"
       }
      }
     },
     "localname": "CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableDiscountMovementScheduleRollForwardTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_ChargeOffOfFinanceReceivablesPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Charge Off Of Finance Receivables [Policy Text Block]",
        "label": "Charge Off Of Finance Receivables Policy [Text Block]",
        "terseLabel": "Charge-Offs on Loans"
       }
      }
     },
     "localname": "ChargeOffOfFinanceReceivablesPolicyTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_ClassifiedAccrualMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Classified accrual.",
        "label": "Classified Accrual [Member]",
        "terseLabel": "Classified- accrual"
       }
      }
     },
     "localname": "ClassifiedAccrualMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_ClassifiedNonAccrualMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Classified non accrual.",
        "label": "Classified Non Accrual [Member]",
        "terseLabel": "Classified- non-accrual"
       }
      }
     },
     "localname": "ClassifiedNonAccrualMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_CollateralDependentLoansFairValueDisclosure": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_AssetsFairValueDisclosure",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Collateral dependent loans fair value disclosure.",
        "label": "Collateral Dependent Loans Fair Value Disclosure",
        "terseLabel": "Collateral-dependent loans"
       }
      }
     },
     "localname": "CollateralDependentLoansFairValueDisclosure",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_CommercialBankingBusinessSegmentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Commercial banking business segment.",
        "label": "Commercial Banking Business Segment [Member]",
        "terseLabel": "Commercial Banking"
       }
      }
     },
     "localname": "CommercialBankingBusinessSegmentMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfGoodwillDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_CommercialFinanceMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Commercial finance.",
        "label": "Commercial Finance [Member]",
        "terseLabel": "Commercial Finance"
       }
      }
     },
     "localname": "CommercialFinanceMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_CommercialFinanceReportingUnitMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Commercial finance reporting unit.",
        "label": "Commercial Finance Reporting Unit [Member]",
        "terseLabel": "Commercial Finance"
       }
      }
     },
     "localname": "CommercialFinanceReportingUnitMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Commercial mortgage backed securities issued by US government sponsored enterprises.",
        "label": "Commercial Mortgage Backed Securities Issued By U S Government Sponsored Enterprises [Member]",
        "terseLabel": "U.S. government/sponsored agency \u2013 Commercial"
       }
      }
     },
     "localname": "CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_CommitmentsExtendedOnAffordableHousingInvestmentCredits": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Commitments extended on affordable housing investment credits.",
        "label": "Commitments Extended On Affordable Housing Investment Credits",
        "terseLabel": "Commitments extended during the period on affordable housing investment credits"
       }
      }
     },
     "localname": "CommitmentsExtendedOnAffordableHousingInvestmentCredits",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_CommitmentsLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Commitments line Items",
        "label": "Commitments [Line Items]",
        "terseLabel": "Commitments [Line Items]"
       }
      }
     },
     "localname": "CommitmentsLineItems",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_CommonEquityTier1CapitalRatioMinimumStated": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Common equity tier 1 capital ratio minimum stated.",
        "label": "Common Equity Tier1 Capital Ratio Minimum Stated",
        "verboseLabel": "Common equity Tier 1 Capital ratio, minimum stated"
       }
      }
     },
     "localname": "CommonEquityTier1CapitalRatioMinimumStated",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsParentheticalDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_CommonStockholdersEquityAttributableToParent": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10040.0,
       "parentTag": "us-gaap_StockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Common Stockholders' Equity Attributable to Parent",
        "label": "Common Stockholders Equity Attributable To Parent",
        "totalLabel": "Total Common Stockholders\u2019 Equity"
       }
      }
     },
     "localname": "CommonStockholdersEquityAttributableToParent",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_ComponentsOfNetInvestmentInFinanceReceivablesTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Components of net investment in finance receivables.",
        "label": "Components Of Net Investment In Finance Receivables Table [Text Block]",
        "terseLabel": "Components Of Net Investment"
       }
      }
     },
     "localname": "ComponentsOfNetInvestmentInFinanceReceivablesTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_ConsumerAndCommunityBankingMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Consumer and community banking.",
        "label": "Consumer And Community Banking [Member]",
        "terseLabel": "Consumer and Community Banking",
        "verboseLabel": "Consumer and Community Banking - SBA Loans"
       }
      }
     },
     "localname": "ConsumerAndCommunityBankingMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_ConsumerBankingBusinessSegmentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Consumer banking business segment.",
        "label": "Consumer Banking Business Segment [Member]",
        "terseLabel": "Consumer Banking"
       }
      }
     },
     "localname": "ConsumerBankingBusinessSegmentMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfGoodwillDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_ConsumerBankingMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Consumer banking.",
        "label": "Consumer Banking [Member]",
        "terseLabel": "Consumer Banking"
       }
      }
     },
     "localname": "ConsumerBankingMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_ConsumerBankingReportingUnitMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Consumer banking reporting unit.",
        "label": "Consumer Banking Reporting Unit [Member]",
        "terseLabel": "Consumer Banking"
       }
      }
     },
     "localname": "ConsumerBankingReportingUnitMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_ConsumerMortgageMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Consumer Mortgage.",
        "label": "Consumer Mortgage [Member]",
        "terseLabel": "Consumer Mortgage"
       }
      }
     },
     "localname": "ConsumerMortgageMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_CoronavirusAidReliefAndEconomicSecurityActCARESActAndInteragencyStatementPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Coronavirus Aid, Relief, and Economic Security Act (the CARES Act) and Interagency Statement.",
        "label": "Coronavirus Aid Relief And Economic Security Act C A R E S Act And Interagency Statement Policy [Text Block]",
        "terseLabel": "Coronavirus Aid, Relief, and Economic Security Act (the CARES Act) and Interagency Statement"
       }
      }
     },
     "localname": "CoronavirusAidReliefAndEconomicSecurityActCARESActAndInteragencyStatementPolicyTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_CoveredLoansMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Covered Loans.",
        "label": "Covered Loans [Member]",
        "terseLabel": "Covered Loans"
       }
      }
     },
     "localname": "CoveredLoansMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_CreditBalancesOfFactoringClients": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10110.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Credit balances of factoring clients.",
        "label": "Credit Balances Of Factoring Clients",
        "negatedLabel": "Credit balances of factoring clients",
        "terseLabel": "Credit balances of factoring clients"
       }
      }
     },
     "localname": "CreditBalancesOfFactoringClients",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_CustomerRelationshipsandTradeNamesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Customer Relationships and Trade Names [Member]",
        "label": "Customer Relationshipsand Trade Names [Member]",
        "terseLabel": "Customer Relationships and Trade Names"
       }
      }
     },
     "localname": "CustomerRelationshipsandTradeNamesMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_DeferredPurchaseAgreementCreditProtectionAmountProvidedToClients": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Deferred Purchase Agreement Credit Protection, Amount Provided To Clients.",
        "label": "Deferred Purchase Agreement Credit Protection Amount Provided To Clients",
        "terseLabel": "DPA credit protection provided to clients"
       }
      }
     },
     "localname": "DeferredPurchaseAgreementCreditProtectionAmountProvidedToClients",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DeferredPurchaseAgreementsCreditLineAgreementsCancellationNoticePeriod": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Deferred Purchase Agreements, Credit Line Agreements, Cancellation Notice Period.",
        "label": "Deferred Purchase Agreements Credit Line Agreements Cancellation Notice Period",
        "terseLabel": "DPA credit line agreements, cancellation notice period"
       }
      }
     },
     "localname": "DeferredPurchaseAgreementsCreditLineAgreementsCancellationNoticePeriod",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "cit_DeferredPurchaseAgreementsCreditLineAgreementsNetOfDeferredPurchaseAgreementCreditProtection": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Deferred Purchase Agreements, Credit Line Agreements Net Of Deferred Purchase Agreement Credit Protection",
        "label": "Deferred Purchase Agreements Credit Line Agreements Net Of Deferred Purchase Agreement Credit Protection",
        "terseLabel": "DPA credit line agreements net of deferred purchase agreement credit protection"
       }
      }
     },
     "localname": "DeferredPurchaseAgreementsCreditLineAgreementsNetOfDeferredPurchaseAgreementCreditProtection",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DeferredPurchaseAgreementsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Deferred Purchase Agreements [Member]",
        "label": "Deferred Purchase Agreements [Member]",
        "terseLabel": "Deferred Purchase Agreements"
       }
      }
     },
     "localname": "DeferredPurchaseAgreementsMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_DeferredPurchaseCreditProtectionAgreementsBorrowingsByClient": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Deferred purchase credit protection agreements, borrowings by client.",
        "label": "Deferred Purchase Credit Protection Agreements Borrowings By Client",
        "terseLabel": "DPA, borrowings by client"
       }
      }
     },
     "localname": "DeferredPurchaseCreditProtectionAgreementsBorrowingsByClient",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DeferredPurchaseCreditProtectionAgreementsNoncurrent": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10060.0,
       "parentTag": "cit_DeferredPurchaseCreditProtectionAgreementsTotalOutstanding",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Deferred Purchase Credit Protection Agreements Noncurrent",
        "label": "Deferred Purchase Credit Protection Agreements Noncurrent",
        "terseLabel": "Deferred purchase credit protection agreements - Due to Expire After One Year"
       }
      }
     },
     "localname": "DeferredPurchaseCreditProtectionAgreementsNoncurrent",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DeferredPurchaseCreditProtectionAgreementsTotalOutstanding": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Deferred purchase credit protection agreements total outstanding",
        "label": "Deferred Purchase Credit Protection Agreements Total Outstanding",
        "totalLabel": "Deferred purchase credit protection agreements - Total Outstanding"
       }
      }
     },
     "localname": "DeferredPurchaseCreditProtectionAgreementsTotalOutstanding",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DeferredPurchaseCreditProtectionAgreementsWithinOneYear": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10050.0,
       "parentTag": "cit_DeferredPurchaseCreditProtectionAgreementsTotalOutstanding",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Deferred purchase credit protection agreements within one year",
        "label": "Deferred Purchase Credit Protection Agreements Within One Year",
        "terseLabel": "Deferred purchase credit protection agreements - Due to Expire Within One Year"
       }
      }
     },
     "localname": "DeferredPurchaseCreditProtectionAgreementsWithinOneYear",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DepositsIncludingAccruedInterest": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total amount of interest-bearing deposit liabilities, which may include brokered, retail, demand, checking, notice of withdrawal, money market and other interest-bearing deposits.",
        "label": "Deposits Including Accrued Interest",
        "negatedLabel": "Deposits"
       }
      }
     },
     "localname": "DepositsIncludingAccruedInterest",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DerivativeAssetFairValueGrossLiabilityNotOffset": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative asset fair value gross liability not offset.",
        "label": "Derivative Asset Fair Value Gross Liability Not Offset",
        "negatedLabel": "Less: Gross amounts not offset in the Consolidated Balance Sheets, Asset Fair Value"
       }
      }
     },
     "localname": "DerivativeAssetFairValueGrossLiabilityNotOffset",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DerivativeAssetSubjectToMasterNettingArrangementDeduction": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative asset subject to master netting arrangement deduction.",
        "label": "Derivative Asset Subject To Master Netting Arrangement Deduction",
        "negatedLabel": "Less: Amounts subject to master netting agreements, Asset Fair Value"
       }
      }
     },
     "localname": "DerivativeAssetSubjectToMasterNettingArrangementDeduction",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DerivativeCollateralNotionalAmount": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative collateral notional amount.",
        "label": "Derivative Collateral Notional Amount",
        "terseLabel": "Cash collateral pledged (received) subject to master netting agreements, Notional Amount"
       }
      }
     },
     "localname": "DerivativeCollateralNotionalAmount",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DerivativeGainLossRecognizedInOtherComprehensiveIncome": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative gain (loss) recognized in other comprehensive income.",
        "label": "Derivative Gain Loss Recognized In Other Comprehensive Income",
        "terseLabel": "Total change in AOCI for period"
       }
      }
     },
     "localname": "DerivativeGainLossRecognizedInOtherComprehensiveIncome",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DerivativeLiabilityFairValueGrossAssetNotOffset": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative liability fair value gross asset not offset.",
        "label": "Derivative Liability Fair Value Gross Asset Not Offset",
        "terseLabel": "Less: Gross amounts not offset in the Consolidated Balance Sheets, Liability Fair Value"
       }
      }
     },
     "localname": "DerivativeLiabilityFairValueGrossAssetNotOffset",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DerivativeLiabilitySubjectToMasterNettingArrangementDeduction": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative liability subject to master netting arrangement deduction.",
        "label": "Derivative Liability Subject To Master Netting Arrangement Deduction",
        "terseLabel": "Less: Amounts subject to master netting agreements, Liability Fair Value"
       }
      }
     },
     "localname": "DerivativeLiabilitySubjectToMasterNettingArrangementDeduction",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DerivativeNotionalAmountNotOffset": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative notional amount not offset.",
        "label": "Derivative Notional Amount Not Offset",
        "terseLabel": "Less: Gross amounts not offset in the Consolidated Balance Sheets, Notional Amount"
       }
      }
     },
     "localname": "DerivativeNotionalAmountNotOffset",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DerivativeNotionalAmountOffset": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative notional amount offset.",
        "label": "Derivative Notional Amount Offset",
        "terseLabel": "Less: Gross amounts offset in the Consolidated Balance Sheets, Notional Amount"
       }
      }
     },
     "localname": "DerivativeNotionalAmountOffset",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DerivativeNotionalAmountOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative notional amount offset against collateral net of not subject to master netting arrangement policy election.",
        "label": "Derivative Notional Amount Offset Against Collateral Net Of Not Subject To Master Netting Arrangement Policy Election",
        "terseLabel": "Total net derivative fair values, Notional Amount"
       }
      }
     },
     "localname": "DerivativeNotionalAmountOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_DerivativeNotionalAmountSubjectToMasterNettingArrangementDeduction": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative notional amount subject to master netting arrangement deduction.",
        "label": "Derivative Notional Amount Subject To Master Netting Arrangement Deduction",
        "terseLabel": "Less: Amounts subject to master netting agreements, Notional Amount"
       }
      }
     },
     "localname": "DerivativeNotionalAmountSubjectToMasterNettingArrangementDeduction",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_ExtendedLineOfCreditFacilityExpirationDate1": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Extended line of credit facility expiration date 1.",
        "label": "Extended Line Of Credit Facility Expiration Date1",
        "terseLabel": "Revolving credit facility, extended maturity date"
       }
      }
     },
     "localname": "ExtendedLineOfCreditFacilityExpirationDate1",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "dateItemType"
    },
    "cit_FICONotRequiredMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "FICO not required.",
        "label": "F I C O Not Required [Member]",
        "terseLabel": "F I C O Not Required"
       }
      }
     },
     "localname": "FICONotRequiredMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_FICOScoreGreaterThanOrEqualTo660AndLessThan730Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "FICO Score, greater than or equal to 660 and less than 730",
        "label": "F I C O Score Greater Than Or Equal To660 And Less Than730 [Member]",
        "terseLabel": "Greater than or Equal to 660 and Less than 730"
       }
      }
     },
     "localname": "FICOScoreGreaterThanOrEqualTo660AndLessThan730Member",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_FICOScoreGreaterThanOrEqualTo730Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "FICO score, greater than or equal to 730.",
        "label": "F I C O Score Greater Than Or Equal To730 [Member]",
        "terseLabel": "Greater than or Equal to 730"
       }
      }
     },
     "localname": "FICOScoreGreaterThanOrEqualTo730Member",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_FICOScoreLessThan660Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "FICO score, less than 660.",
        "label": "F I C O Score Less Than660 [Member]",
        "terseLabel": "Less than 660"
       }
      }
     },
     "localname": "FICOScoreLessThan660Member",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_FICOScoreNotRequiredMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "FICO score not required.",
        "label": "F I C O Score Not Required [Member]",
        "terseLabel": "FICO Score Not Required"
       }
      }
     },
     "localname": "FICOScoreNotRequiredMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_FairValueDisclosureLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value disclosure.",
        "label": "Fair Value Disclosure [Line Items]",
        "terseLabel": "Fair Value Disclosure [Line Items]"
       }
      }
     },
     "localname": "FairValueDisclosureLineItems",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_FairValueDisclosureTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value disclosure.",
        "label": "Fair Value Disclosure [Table]",
        "terseLabel": "Fair Value Disclosure [Table]"
       }
      }
     },
     "localname": "FairValueDisclosureTable",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySalesPayDownsAndAdjustments": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value measurement with unobservable inputs reconciliation recurring basis liability sales pay downs and adjustments.",
        "label": "Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Sales Pay Downs And Adjustments",
        "terseLabel": "Sales, paydowns, and adjustments"
       }
      }
     },
     "localname": "FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySalesPayDownsAndAdjustments",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FdicTrueUpLiability": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_LiabilitiesFairValueDisclosure",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "FDIC true-up liability.",
        "label": "Fdic True Up Liability",
        "negatedLabel": "FDIC True-up liability"
       }
      }
     },
     "localname": "FdicTrueUpLiability",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FdicTrueUpLiabilityMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "FDIC true-up liability.",
        "label": "Fdic True Up Liability [Member]",
        "terseLabel": "FDIC True-up Liability"
       }
      }
     },
     "localname": "FdicTrueUpLiabilityMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_FinanceReceivablesNonAccrualStatusByTypeOfHoldingLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Finance receivables non-accrual status by type of holding.",
        "label": "Finance Receivables Non Accrual Status By Type Of Holding [Line Items]",
        "terseLabel": "Finance Receivables Non Accrual Status By Type Of Holding [Line Items]"
       }
      }
     },
     "localname": "FinanceReceivablesNonAccrualStatusByTypeOfHoldingLineItems",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_FinanceReceivablesNonAccrualStatusByTypeOfHoldingTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Finance receivables non-accrual status by type of holding.",
        "label": "Finance Receivables Non Accrual Status By Type Of Holding [Table]",
        "terseLabel": "Finance Receivables Non Accrual Status By Type Of Holding [Table]"
       }
      }
     },
     "localname": "FinanceReceivablesNonAccrualStatusByTypeOfHoldingTable",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_FinancingAndLeasingAssetsOnCommitmentsAmountOutstanding": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing and leasing assets on commitments amount outstanding.",
        "label": "Financing And Leasing Assets On Commitments Amount Outstanding",
        "totalLabel": "Financing assets - Total Outstanding"
       }
      }
     },
     "localname": "FinancingAndLeasingAssetsOnCommitmentsAmountOutstanding",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FinancingAndLeasingAssetsOnCommitmentsCurrent": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10110.0,
       "parentTag": "cit_FinancingAndLeasingAssetsOnCommitmentsAmountOutstanding",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing and leasing assets on commitments current.",
        "label": "Financing And Leasing Assets On Commitments Current",
        "terseLabel": "Financing assets - Due to Expire Within One Year"
       }
      }
     },
     "localname": "FinancingAndLeasingAssetsOnCommitmentsCurrent",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FinancingAndLeasingAssetsOnCommitmentsNoncurrent": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10120.0,
       "parentTag": "cit_FinancingAndLeasingAssetsOnCommitmentsAmountOutstanding",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing and leasing assets on commitments noncurrent",
        "label": "Financing And Leasing Assets On Commitments Noncurrent",
        "terseLabel": "Financing assets - Due to Expire After One Year"
       }
      }
     },
     "localname": "FinancingAndLeasingAssetsOnCommitmentsNoncurrent",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FinancingCommitmentsToTradeFinanceClientsThatAreCancelableOnlyAfterANoticePeriodAmount": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing Commitments To Trade Finance Clients That Are Cancelable Only After A Notice Period, Amount",
        "label": "Financing Commitments To Trade Finance Clients That Are Cancelable Only After A Notice Period Amount",
        "terseLabel": "Financing commitments to trade finance clients that are cancelable only after a notice period, amount"
       }
      }
     },
     "localname": "FinancingCommitmentsToTradeFinanceClientsThatAreCancelableOnlyAfterANoticePeriodAmount",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FinancingCommitmentsToTradeFinanceClientsThatAreCancelableOnlyAfterANoticePeriodTypicalNoticePeriod": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing Commitments To Trade Finance Clients That Are Cancelable Only After A Notice Period, Typical Notice Period",
        "label": "Financing Commitments To Trade Finance Clients That Are Cancelable Only After A Notice Period Typical Notice Period",
        "terseLabel": "Typical notice period"
       }
      }
     },
     "localname": "FinancingCommitmentsToTradeFinanceClientsThatAreCancelableOnlyAfterANoticePeriodTypicalNoticePeriod",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "cit_FinancingReceivableAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing receivable.",
        "label": "Financing Receivable [Abstract]",
        "terseLabel": "Loans receivables"
       }
      }
     },
     "localname": "FinancingReceivableAbstract",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_FinancingReceivableAccruedInterestReversedToNonaccrualStatus": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing receivable accrued interest reversed to nonaccrual status.",
        "label": "Financing Receivable Accrued Interest Reversed To Nonaccrual Status",
        "terseLabel": "Accrued interest reversed to non-accrual status"
       }
      }
     },
     "localname": "FinancingReceivableAccruedInterestReversedToNonaccrualStatus",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FinancingReceivableAllowanceForCreditLossesMinimumAmountToBeIndividuallyEvaluatedforImpairment": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing Receivable, Allowance For Credit Losses, Minimum Amount To Be Individually Evaluated for Impairment",
        "label": "Financing Receivable Allowance For Credit Losses Minimum Amount To Be Individually Evaluatedfor Impairment",
        "terseLabel": "Minimum value of loans to be individually assessed for impairment"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossesMinimumAmountToBeIndividuallyEvaluatedforImpairment",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FinancingReceivableRevolvingLoansConvertedToTermLoansAmortizedCostBasis": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails": {
       "order": 10080.0,
       "parentTag": "us-gaap_FinancingReceivableAfterDeferredIncomeOffset",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing receivable revolving loans converted to term loans amortized cost basis.",
        "label": "Financing Receivable Revolving Loans Converted To Term Loans Amortized Cost Basis",
        "terseLabel": "Revolving Loans Converted to Term Loans Amortized Cost Basis"
       }
      }
     },
     "localname": "FinancingReceivableRevolvingLoansConvertedToTermLoansAmortizedCostBasis",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FiniteLivedIntangibleAssetsAmortizationRentalsBelowCurrentMarketRates": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Finite lived intangible assets amortization rentals below current market rates.",
        "label": "Finite Lived Intangible Assets Amortization Rentals Below Current Market Rates",
        "negatedLabel": "Intangible Assets Amortization, Rentals Below Current Market Rates"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsAmortizationRentalsBelowCurrentMarketRates",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FiniteLivedIntangibleAssetsRentalsBelowCurrentMarketRates": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Finite lived intangible assets rentals below current market rates.",
        "label": "Finite Lived Intangible Assets Rentals Below Current Market Rates",
        "negatedPeriodEndLabel": "Intangible Assets, Rentals Below Current Market Rates",
        "negatedPeriodStartLabel": "Intangible Assets, Rentals Below Current Market Rates",
        "negatedTerseLabel": "Intangible Assets, Rentals Below Current Market Rates"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsRentalsBelowCurrentMarketRates",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_FivePointSixTwoFivePercentageNonCumulativePerpetualPreferredStockSeriesBMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Five point six two five percentage non cumulative perpetual preferred stock series B.",
        "label": "Five Point Six Two Five Percentage Non Cumulative Perpetual Preferred Stock Series B [Member]",
        "terseLabel": "5.625% Non-Cumulative Perpetual Preferred Stock, Series B"
       }
      }
     },
     "localname": "FivePointSixTwoFivePercentageNonCumulativePerpetualPreferredStockSeriesBMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_ForeignCurrencyForwardContractMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Foreign currency forward contract.",
        "label": "Foreign Currency Forward Contract [Member]",
        "terseLabel": "Foreign Currency Forward Contract"
       }
      }
     },
     "localname": "ForeignCurrencyForwardContractMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_GainsLossesOnExtinguishmentOfDebtIncludingDiscontinuedOperations": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10250.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity including discontinued operations.",
        "label": "Gains Losses On Extinguishment Of Debt Including Discontinued Operations",
        "negatedLabel": "Loss on debt extinguishment and deposit redemption"
       }
      }
     },
     "localname": "GainsLossesOnExtinguishmentOfDebtIncludingDiscontinuedOperations",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_GuaranteesAcceptancesAndOtherRecourseObligationsNoncurrent": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10040.0,
       "parentTag": "cit_GuaranteesAcceptancesAndOtherRecourseObligationsTotalOutstanding",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Guarantees Acceptances and Other Recourse Obligations Noncurrent",
        "label": "Guarantees Acceptances And Other Recourse Obligations Noncurrent",
        "terseLabel": "Guarantees, acceptances and other recourse obligations - Due to Expire After One Year"
       }
      }
     },
     "localname": "GuaranteesAcceptancesAndOtherRecourseObligationsNoncurrent",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_GuaranteesAcceptancesAndOtherRecourseObligationsTotalOutstanding": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Guarantees acceptances and other recourse obligations - total outstanding",
        "label": "Guarantees Acceptances And Other Recourse Obligations Total Outstanding",
        "totalLabel": "Guarantees, acceptances and other recourse obligations - Total Outstanding"
       }
      }
     },
     "localname": "GuaranteesAcceptancesAndOtherRecourseObligationsTotalOutstanding",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_GuaranteesAcceptancesAndOtherRecourseObligationsWithinOneYear": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10030.0,
       "parentTag": "cit_GuaranteesAcceptancesAndOtherRecourseObligationsTotalOutstanding",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Guarantees acceptances and other recourse obligations within one year",
        "label": "Guarantees Acceptances And Other Recourse Obligations Within One Year",
        "terseLabel": "Guarantees, acceptances and other recourse obligations - Due to Expire Within One Year"
       }
      }
     },
     "localname": "GuaranteesAcceptancesAndOtherRecourseObligationsWithinOneYear",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_HedgedItemMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Hedged item.",
        "label": "Hedged Item [Member]",
        "terseLabel": "Recognized on Hedged Item"
       }
      }
     },
     "localname": "HedgedItemMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_HighQualityLiquidSecuritiesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "High quality liquid securities.",
        "label": "High Quality Liquid Securities [Member]",
        "terseLabel": "High quality liquid securities"
       }
      }
     },
     "localname": "HighQualityLiquidSecuritiesMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_ImpactToCommonEquityTierOneCapital": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Impact to common equity tier one capital.",
        "label": "Impact To Common Equity Tier One Capital",
        "terseLabel": "Increase to CET1 Capital"
       }
      }
     },
     "localname": "ImpactToCommonEquityTierOneCapital",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_ImpairedFinancingReceivableInterestIncome": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Impaired financing receivable, interest income.",
        "label": "Impaired Financing Receivable Interest Income",
        "terseLabel": "Interest income recorded"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableInterestIncome",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_ImpairedLoansFairValueDisclosure": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_AssetsFairValueDisclosure",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Impaired Loans Fair Value Disclosure",
        "label": "Impaired Loans Fair Value Disclosure",
        "terseLabel": "Impaired loans"
       }
      }
     },
     "localname": "ImpairedLoansFairValueDisclosure",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_ImpairedLoansMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Impaired loans.",
        "label": "Impaired Loans [Member]",
        "terseLabel": "Impaired Loans"
       }
      }
     },
     "localname": "ImpairedLoansMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_ImpairmentLossOnTaxCreditInvestments": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Impairment loss on tax credit investments.",
        "label": "Impairment Loss On Tax Credit Investments",
        "negatedLabel": "Impairment loss on tax credit investments"
       }
      }
     },
     "localname": "ImpairmentLossOnTaxCreditInvestments",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_InitialNonPurchasedCreditDeterioratedCharge": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Initial non-purchased credit deteriorated charge.",
        "label": "Initial Non Purchased Credit Deteriorated Charge",
        "terseLabel": "Initial non-PCD Charge"
       }
      }
     },
     "localname": "InitialNonPurchasedCreditDeterioratedCharge",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_InitialNonPurchasedCreditDeterioratedChargePercentage": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Initial non-purchased credit deteriorated charge percentage.",
        "label": "Initial Non Purchased Credit Deteriorated Charge Percentage",
        "terseLabel": "Initial non-PCD charge percentage"
       }
      }
     },
     "localname": "InitialNonPurchasedCreditDeterioratedChargePercentage",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_InterestBenefitExpenseNet": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Interest benefit (expense) net.",
        "label": "Interest Benefit Expense Net",
        "negatedLabel": "Interest expense (benefit)"
       }
      }
     },
     "localname": "InterestBenefitExpenseNet",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_InterestIncomeInterestBearingCash": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfInterestAndDividendIncomeDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_InterestAndDividendIncomeSecurities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Interest income interest bearing cash.",
        "label": "Interest Income Interest Bearing Cash",
        "terseLabel": "Interest income - interest-bearing cash"
       }
      }
     },
     "localname": "InterestIncomeInterestBearingCash",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfInterestAndDividendIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_InterestRateContractsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Interest rate contracts.",
        "label": "Interest Rate Contracts [Member]",
        "terseLabel": "Interest rate contracts"
       }
      }
     },
     "localname": "InterestRateContractsMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_LeaseIncomeIncludingIncomeOnLeverageLeases": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Lease income, including income on leverage leases.",
        "label": "Lease Income Including Income On Leverage Leases",
        "totalLabel": "Total lease income"
       }
      }
     },
     "localname": "LeaseIncomeIncludingIncomeOnLeverageLeases",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_LeasesLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Leases.",
        "label": "Leases [Line Items]",
        "terseLabel": "Leases [Line Items]"
       }
      }
     },
     "localname": "LeasesLineItems",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_LeasesOfLesseeAndLessorDisclosureTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Leases of lessee and lessor disclosure.",
        "label": "Leases Of Lessee And Lessor Disclosure [Text Block]",
        "terseLabel": "LEASES"
       }
      }
     },
     "localname": "LeasesOfLesseeAndLessorDisclosureTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeases"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_LeasesTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Leases.",
        "label": "Leases [Table]",
        "terseLabel": "Leases [Table]"
       }
      }
     },
     "localname": "LeasesTable",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_LegacyCITCECLAdoptionMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Legacy CIT CECL Adoption.",
        "label": "Legacy C I T C E C L Adoption [Member]",
        "terseLabel": "Legacy CIT CECL Adoption"
       }
      }
     },
     "localname": "LegacyCITCECLAdoptionMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_LegacyConsumerMortgagesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Legacy Consumer Mortgages.",
        "label": "Legacy Consumer Mortgages [Member]",
        "terseLabel": "Legacy Consumer Mortgages",
        "verboseLabel": "Legacy Consumer Mortgages"
       }
      }
     },
     "localname": "LegacyConsumerMortgagesMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_LendingAssetsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Lending assets.",
        "label": "Lending Assets [Member]",
        "terseLabel": "Lending assets"
       }
      }
     },
     "localname": "LendingAssetsMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_LessorLeaseIncomeTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Lessor, lease income.",
        "label": "Lessor Lease Income Table [Text Block]",
        "terseLabel": "Schedule of Lease Income Related to Company's Operating and Finance Leases"
       }
      }
     },
     "localname": "LessorLeaseIncomeTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_LessorLeasedEquipmentPropertyTaxReimbursementsDueFromCustomers": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Lessor, leased equipment property tax reimbursements due from customers.",
        "label": "Lessor Leased Equipment Property Tax Reimbursements Due From Customers",
        "terseLabel": "Leased equipment property tax reimbursements due from customers"
       }
      }
     },
     "localname": "LessorLeasedEquipmentPropertyTaxReimbursementsDueFromCustomers",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_LessorRevenueOnInsuranceCoverageForLeasedEquipment": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Lessor, revenue on insurance coverage for leased equipment.",
        "label": "Lessor Revenue On Insurance Coverage For Leased Equipment",
        "terseLabel": "Revenue related to insurance coverage Commercial Finance leased equipment"
       }
      }
     },
     "localname": "LessorRevenueOnInsuranceCoverageForLeasedEquipment",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_LiabilityMeasurementInput": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Liability measurement input.",
        "label": "Liability Measurement Input",
        "terseLabel": "Liability measurement input"
       }
      }
     },
     "localname": "LiabilityMeasurementInput",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "decimalItemType"
    },
    "cit_LoanToValueNotAvailableMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loan-to-Value not available.",
        "label": "Loan To Value Not Available [Member]",
        "terseLabel": "Loan To Value Not Available"
       }
      }
     },
     "localname": "LoanToValueNotAvailableMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_LoansInProcessOfForeclosureLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loans in process of foreclosure.",
        "label": "Loans In Process Of Foreclosure [Line Items]",
        "terseLabel": "Loans In Process Of Foreclosure [Line Items]"
       }
      }
     },
     "localname": "LoansInProcessOfForeclosureLineItems",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansInProcessOfForeclosureParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_LoansandLeasesReceivableNonperformingPeriodPastDue": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loans and Leases Receivable, Nonperforming, Period Past Due",
        "label": "Loansand Leases Receivable Nonperforming Period Past Due",
        "terseLabel": "Period for which loans are considered past due"
       }
      }
     },
     "localname": "LoansandLeasesReceivableNonperformingPeriodPastDue",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "cit_LoansandLeasesReceivableNonperformingPeriodPastDueForNonAccrualStatus": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loans and Leases Receivable, Nonperforming, Period Past Due For Non Accrual Status",
        "label": "Loansand Leases Receivable Nonperforming Period Past Due For Non Accrual Status",
        "terseLabel": "Period past due when loans go into non accrual status"
       }
      }
     },
     "localname": "LoansandLeasesReceivableNonperformingPeriodPastDueForNonAccrualStatus",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "cit_Ltv101To125PercentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "LTV 101 to 125 Percent.",
        "label": "Ltv101 To125 Percent [Member]",
        "terseLabel": "LTV 101% \u2013 125%"
       }
      }
     },
     "localname": "Ltv101To125PercentMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_LtvGreaterThan125PercentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loan-to-value (LTV) greater than 125%. Element name and standard label in LTV Greater Than [low end numeric value] Percent [Member] or LTV Less Than [high end numeric value] Percent [Member] formats.",
        "label": "Ltv Greater Than125 Percent [Member]",
        "terseLabel": "LTV Greater Than 125 Percent"
       }
      }
     },
     "localname": "LtvGreaterThan125PercentMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_MarginDepositLiabilities": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Margin Deposit Liabilities",
        "label": "Margin Deposit Liabilities",
        "terseLabel": "Variable margin balances, liabilities"
       }
      }
     },
     "localname": "MarginDepositLiabilities",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_MeasurementInputBorrowerRateMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement input borrower rate.",
        "label": "Measurement Input Borrower Rate [Member]",
        "terseLabel": "Borrower Rate"
       }
      }
     },
     "localname": "MeasurementInputBorrowerRateMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_MortgageServicingRightsFairValueDisclosure": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails": {
       "order": 10050.0,
       "parentTag": "us-gaap_AssetsFairValueDisclosure",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Mortgage servicing rights fair value disclosure.",
        "label": "Mortgage Servicing Rights Fair Value Disclosure",
        "terseLabel": "Mortgage Servicing Rights"
       }
      }
     },
     "localname": "MortgageServicingRightsFairValueDisclosure",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_MutualOfOmahaBankMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Mutual of Omaha Bank.",
        "label": "Mutual Of Omaha Bank [Member]",
        "terseLabel": "MOB",
        "verboseLabel": "Mutual of Omaha Bank (\"MOB\")"
       }
      }
     },
     "localname": "MutualOfOmahaBankMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSelectedUnauditedProFormaFinancialInformationDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_NetUnamortizedDeferredFeesAndCosts": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Net unamortized deferred fees and costs.",
        "label": "Net Unamortized Deferred Fees And Costs",
        "terseLabel": "Net unamortized deferred costs and (fees)"
       }
      }
     },
     "localname": "NetUnamortizedDeferredFeesAndCosts",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansComponentsOfNetInvestmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_NoFICOScoreAvailableMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "No FICO score available.",
        "label": "No F I C O Score Available [Member]",
        "terseLabel": "No FICO Score Available"
       }
      }
     },
     "localname": "NoFICOScoreAvailableMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_NoLTVRequiredMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "No LTV required.",
        "label": "No L T V Required [Member]",
        "terseLabel": "No LTV required"
       }
      }
     },
     "localname": "NoLTVRequiredMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_NonCoveredLoansMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Non-covered Loans.",
        "label": "Non Covered Loans [Member]",
        "terseLabel": "Non-covered Loans"
       }
      }
     },
     "localname": "NonCoveredLoansMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_NonMarketableSecuritiesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Non-marketable securities.",
        "label": "Non Marketable Securities [Member]",
        "terseLabel": "Non-marketable securities"
       }
      }
     },
     "localname": "NonMarketableSecuritiesMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_NoninterestOperatingExpenses": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10150.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Noninterest operating expenses.",
        "label": "Noninterest Operating Expenses",
        "terseLabel": "Operating expenses"
       }
      }
     },
     "localname": "NoninterestOperatingExpenses",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_NumberOfBranches": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number Of Branches.",
        "label": "Number Of Branches",
        "terseLabel": "Number of branches"
       }
      }
     },
     "localname": "NumberOfBranches",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "cit_NumberOfConsolidatedVariableInterestEntities": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of consolidated variable interest entities.",
        "label": "Number Of Consolidated Variable Interest Entities",
        "terseLabel": "Consolidated VIEs"
       }
      }
     },
     "localname": "NumberOfConsolidatedVariableInterestEntities",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesNarrativeDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "cit_NumberOfDomesticOperatingSubsidiariesThatAreGuarantors": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of domestic operating subsidiaries that are guarantors.",
        "label": "Number Of Domestic Operating Subsidiaries That Are Guarantors",
        "terseLabel": "Revolving credit facility, domestic operating subsidiary guarantors"
       }
      }
     },
     "localname": "NumberOfDomesticOperatingSubsidiariesThatAreGuarantors",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "cit_OneWestBankMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "OneWest bank.",
        "label": "One West Bank [Member]",
        "terseLabel": "OneWest Bank",
        "verboseLabel": "OneWest Bank"
       }
      }
     },
     "localname": "OneWestBankMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_OperatingExpensesAndLossOnDebtExtinguishment": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails": {
       "order": 10090.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Operating expenses and loss on debt extinguishment.",
        "label": "Operating Expenses And Loss On Debt Extinguishment",
        "terseLabel": "Operating expenses/loss on debt extinguishment and deposit redemption"
       }
      }
     },
     "localname": "OperatingExpensesAndLossOnDebtExtinguishment",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_OtherAssetsSubjectToFairValueDisclosure": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other assets subject to fair value disclosure.",
        "label": "Other Assets Subject To Fair Value Disclosure",
        "terseLabel": "Other assets subject to fair value disclosure"
       }
      }
     },
     "localname": "OtherAssetsSubjectToFairValueDisclosure",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_OtherContractsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other contracts.",
        "label": "Other Contracts [Member]",
        "terseLabel": "Other contracts"
       }
      }
     },
     "localname": "OtherContractsMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_OtherDerivativeMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other Derivative.",
        "label": "Other Derivative [Member]",
        "terseLabel": "Other Derivative Non qualifying Hedges"
       }
      }
     },
     "localname": "OtherDerivativeMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_OtherLettersOfCreditNoncurrent": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10080.0,
       "parentTag": "cit_OtherLettersOfCreditTotalOutstanding",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other Letters of Credit Noncurrent",
        "label": "Other Letters Of Credit Noncurrent",
        "terseLabel": "Other letters of credit - Due to Expire After One Year"
       }
      }
     },
     "localname": "OtherLettersOfCreditNoncurrent",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_OtherLettersOfCreditTotalOutstanding": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other letters of credit total outstanding",
        "label": "Other Letters Of Credit Total Outstanding",
        "totalLabel": "Other letters of credit - Total Outstanding"
       }
      }
     },
     "localname": "OtherLettersOfCreditTotalOutstanding",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_OtherLettersOfCreditWithinOneYear": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10070.0,
       "parentTag": "cit_OtherLettersOfCreditTotalOutstanding",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other letters of credit within one year",
        "label": "Other Letters Of Credit Within One Year",
        "terseLabel": "Other letters of credit - Due to Expire Within One Year"
       }
      }
     },
     "localname": "OtherLettersOfCreditWithinOneYear",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_OtherLiabilitiesSubjectToFairValueDisclosure": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other liabilities subject to fair value disclosure",
        "label": "Other Liabilities Subject To Fair Value Disclosure",
        "negatedLabel": "Other liabilities subject to fair value disclosure"
       }
      }
     },
     "localname": "OtherLiabilitiesSubjectToFairValueDisclosure",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_OtherNewlyAdoptedAccountingStandardsPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other newly adopted accounting standards.",
        "label": "Other Newly Adopted Accounting Standards Policy [Text Block]",
        "terseLabel": "Other Newly Adopted Accounting Standards"
       }
      }
     },
     "localname": "OtherNewlyAdoptedAccountingStandardsPolicyTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_OtherNonInterestIncomeMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other non interest income.",
        "label": "Other Non Interest Income [Member]",
        "terseLabel": "Other Non-Interest Income"
       }
      }
     },
     "localname": "OtherNonInterestIncomeMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_OtherReservesAdditionalCreditLossReservesForUnfundedLendingCommitmentsLettersOfCreditAndForDeferredPurchaseAgreements": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other reserves additional credit loss reserves for unfunded lending commitments, letters of credit and for deferred purchase agreements.",
        "label": "Other Reserves Additional Credit Loss Reserves For Unfunded Lending Commitments Letters Of Credit And For Deferred Purchase Agreements",
        "terseLabel": "Other reserves"
       }
      }
     },
     "localname": "OtherReservesAdditionalCreditLossReservesForUnfundedLendingCommitmentsLettersOfCreditAndForDeferredPurchaseAgreements",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_OtherSecuredAndStructuredFinancingsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other secured and structured financings",
        "label": "Other Secured And Structured Financings [Member]",
        "terseLabel": "Other secured and structured financings"
       }
      }
     },
     "localname": "OtherSecuredAndStructuredFinancingsMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_OtherSecuritiesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other securities.",
        "label": "Other Securities [Member]",
        "terseLabel": "Other Securities"
       }
      }
     },
     "localname": "OtherSecuritiesMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_PartnershipInvestmentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Partnership Investment [Member]",
        "label": "Partnership Investment [Member]",
        "terseLabel": "Partnership Investment"
       }
      }
     },
     "localname": "PartnershipInvestmentMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_PercentageOfInvestmentsInTroubledDebtRestructurings": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage of investments in troubled debt restructurings.",
        "label": "Percentage Of Investments In Troubled Debt Restructurings",
        "terseLabel": "% Total TDR"
       }
      }
     },
     "localname": "PercentageOfInvestmentsInTroubledDebtRestructurings",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfTdrsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_PercentageOfLoanNet": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage of loan net.",
        "label": "Percentage Of Loan Net",
        "terseLabel": "Percent of loans to total loans"
       }
      }
     },
     "localname": "PercentageOfLoanNet",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_PercentageOfModificationsOnNonAccrual": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage of modifications on non accrual.",
        "label": "Percentage Of Modifications On Non Accrual",
        "terseLabel": "Percent non-accrual"
       }
      }
     },
     "localname": "PercentageOfModificationsOnNonAccrual",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfTdrsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_PercentageOfScalingFactorOfChangeInNonPurchasedWithCreditDeteriorationAllowanceForCreditLossesYearTwo": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage of scaling factor of change in non purchased with credit deterioration allowance for credit losses year two.",
        "label": "Percentage Of Scaling Factor Of Change In Non Purchased With Credit Deterioration Allowance For Credit Losses Year Two",
        "terseLabel": "Percentage of scaling factor of change in Non-PCD ACL year two"
       }
      }
     },
     "localname": "PercentageOfScalingFactorOfChangeInNonPurchasedWithCreditDeteriorationAllowanceForCreditLossesYearTwo",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_PercentageOfScalingFactorOfChangeInReserveForNonPurchasedWithCreditDeteriorationLoans": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage of scaling factor of change in reserve for non-purchased with Credit Deterioration loans.",
        "label": "Percentage Of Scaling Factor Of Change In Reserve For Non Purchased With Credit Deterioration Loans",
        "terseLabel": "Percentage of scaling factor of change in reserve for Non-PCD Loans"
       }
      }
     },
     "localname": "PercentageOfScalingFactorOfChangeInReserveForNonPurchasedWithCreditDeteriorationLoans",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_PercentageOfTransitionalBenefitsRecognizedInRegulatoryCapitalInYearFive": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "percentage of transitional benefits recognized in regulatory capital in year five.",
        "label": "Percentage Of Transitional Benefits Recognized In Regulatory Capital In Year Five",
        "terseLabel": "Percentage of transitional benefits recognized in regulatory capital in year five"
       }
      }
     },
     "localname": "PercentageOfTransitionalBenefitsRecognizedInRegulatoryCapitalInYearFive",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_PercentageOfTransitionalBenefitsRecognizedInRegulatoryCapitalInYearFour": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage of transitional benefits recognized in regulatory capital in year four.",
        "label": "Percentage Of Transitional Benefits Recognized In Regulatory Capital In Year Four",
        "terseLabel": "Percentage of transitional benefits recognized in regulatory capital in year four"
       }
      }
     },
     "localname": "PercentageOfTransitionalBenefitsRecognizedInRegulatoryCapitalInYearFour",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_PercentageOfTransitionalBenefitsRecognizedInRegulatoryCapitalInYearThree": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage of transitional benefits recognized in regulatory capital in year three.",
        "label": "Percentage Of Transitional Benefits Recognized In Regulatory Capital In Year Three",
        "terseLabel": "Percentage of transitional benefits recognized in regulatory capital in year three"
       }
      }
     },
     "localname": "PercentageOfTransitionalBenefitsRecognizedInRegulatoryCapitalInYearThree",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_PledgedAssets": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Pledged assets.",
        "label": "Pledged Assets",
        "terseLabel": "Pledged assets"
       }
      }
     },
     "localname": "PledgedAssets",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_PledgedSecuritiesCarryingValue": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Pledged securities carrying value.",
        "label": "Pledged Securities Carrying Value",
        "terseLabel": "Pledged securities carrying value"
       }
      }
     },
     "localname": "PledgedSecuritiesCarryingValue",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_ProceedsFromAssetAndReceivableSales": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10140.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Proceeds from asset and receivable sales.",
        "label": "Proceeds From Asset And Receivable Sales",
        "terseLabel": "Proceeds from asset and receivable sales"
       }
      }
     },
     "localname": "ProceedsFromAssetAndReceivableSales",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_ProceedsFromSalesAndMaturitiesOfInvestmentSecuritiesAndSecuritiesPurchasedUnderAgreementToResell": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10130.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Proceeds from sales and maturities of investment securities and securities purchased under agreement to resell.",
        "label": "Proceeds From Sales And Maturities Of Investment Securities And Securities Purchased Under Agreement To Resell",
        "terseLabel": "Proceeds from sales and maturities of investment securities and securities purchased under agreement to resell"
       }
      }
     },
     "localname": "ProceedsFromSalesAndMaturitiesOfInvestmentSecuritiesAndSecuritiesPurchasedUnderAgreementToResell",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_PurchaseAccountingAdjustmentPremium": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Purchase accounting adjustment premium.",
        "label": "Purchase Accounting Adjustment Premium",
        "terseLabel": "PAA premium"
       }
      }
     },
     "localname": "PurchaseAccountingAdjustmentPremium",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_PurchasedCreditDeterioratedLoansMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Purchased credit deteriorated loans.",
        "label": "Purchased Credit Deteriorated Loans [Member]",
        "terseLabel": "PCD Loans"
       }
      }
     },
     "localname": "PurchasedCreditDeterioratedLoansMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_PurchasedCreditImpairedLoansWithDeterioratedCreditQualityTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Purchased credit impaired loans with deteriorated credit quality.",
        "label": "Purchased Credit Impaired Loans With Deteriorated Credit Quality Table [Text Block]",
        "terseLabel": "Purchased Credit Impaired Loans With Deteriorated Credit Quality"
       }
      }
     },
     "localname": "PurchasedCreditImpairedLoansWithDeterioratedCreditQualityTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_PurchasesOfInvestmentSecuritiesAndSecuritiesPurchasedUnderAgreementToResell": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10120.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Purchases of investment securities and securities purchased under agreement to resell.",
        "label": "Purchases Of Investment Securities And Securities Purchased Under Agreement To Resell",
        "negatedLabel": "Purchases of investment securities and securities purchased under agreement to resell"
       }
      }
     },
     "localname": "PurchasesOfInvestmentSecuritiesAndSecuritiesPurchasedUnderAgreementToResell",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_RailAndOtherManufacturerPurchaseCommitmentsDueToExpireAfterOneYear": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10020.0,
       "parentTag": "cit_RailAndOtherManufacturerPurchaseCommitmentsTotalOutstanding",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Rail and other manufacturer purchase commitments - due to expire after one year",
        "label": "Rail And Other Manufacturer Purchase Commitments Due To Expire After One Year",
        "terseLabel": "Rail and other purchase commitments - Due to Expire After One Year"
       }
      }
     },
     "localname": "RailAndOtherManufacturerPurchaseCommitmentsDueToExpireAfterOneYear",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_RailAndOtherManufacturerPurchaseCommitmentsDueToExpireWithinOneYear": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10010.0,
       "parentTag": "cit_RailAndOtherManufacturerPurchaseCommitmentsTotalOutstanding",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Rail and other manufacturer purchase commitments - due to expire within one year",
        "label": "Rail And Other Manufacturer Purchase Commitments Due To Expire Within One Year",
        "terseLabel": "Rail and other purchase commitments - Due to Expire Within One Year"
       }
      }
     },
     "localname": "RailAndOtherManufacturerPurchaseCommitmentsDueToExpireWithinOneYear",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_RailAndOtherManufacturerPurchaseCommitmentsTotalOutstanding": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Rail and other manufacturer purchase commitments - total outstanding",
        "label": "Rail And Other Manufacturer Purchase Commitments Total Outstanding",
        "totalLabel": "Rail and other purchase commitments - Total Outstanding"
       }
      }
     },
     "localname": "RailAndOtherManufacturerPurchaseCommitmentsTotalOutstanding",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_RailMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Rail.",
        "label": "Rail [Member]",
        "terseLabel": "Rail"
       }
      }
     },
     "localname": "RailMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_RealEstateFinanceMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Real estate finance.",
        "label": "Real Estate Finance [Member]",
        "terseLabel": "Real Estate Finance"
       }
      }
     },
     "localname": "RealEstateFinanceMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_RealEstateFinanceReportingUnitMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Real estate finance reporting unit.",
        "label": "Real Estate Finance Reporting Unit [Member]",
        "terseLabel": "Real Estate Finance"
       }
      }
     },
     "localname": "RealEstateFinanceReportingUnitMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_RecordedInvestmentTroubledDebtRestructuringRelatedToModifications": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Recorded investment, troubled debt restructuring related to modifications.",
        "label": "Recorded Investment Troubled Debt Restructuring Related To Modifications",
        "terseLabel": "Recorded investment related to modifications qualifying as TDRs that occurred during the quarters"
       }
      }
     },
     "localname": "RecordedInvestmentTroubledDebtRestructuringRelatedToModifications",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfModificationsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_RecordedInvestmentTroubledDebtRestructuringsThatSubsequentlyDefaultedWithinOneYear": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Recorded investment, troubled debt restructurings that subsequently defaulted within one year.",
        "label": "Recorded Investment Troubled Debt Restructurings That Subsequently Defaulted Within One Year",
        "terseLabel": "Recorded investment at the time of default of TDRs that experienced a payment default (payment default is one missed payment) during the quarters and for which the payment default occurred within one year of the modification"
       }
      }
     },
     "localname": "RecordedInvestmentTroubledDebtRestructuringsThatSubsequentlyDefaultedWithinOneYear",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfModificationsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_RegulatoryCapitalRequirementsUnderBankingRegulationsPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Regulatory capital requirements under banking regulations.",
        "label": "Regulatory Capital Requirements Under Banking Regulations Policy [Text Block]",
        "terseLabel": "Regulatory Capital"
       }
      }
     },
     "localname": "RegulatoryCapitalRequirementsUnderBankingRegulationsPolicyTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_ReportingUnitMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Reporting Unit [Member]",
        "label": "Reporting Unit [Member]",
        "terseLabel": "Reporting Units"
       }
      }
     },
     "localname": "ReportingUnitMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Residential mortgage backed securities issued by US government sponsored enterprises.",
        "label": "Residential Mortgage Backed Securities Issued By U S Government Sponsored Enterprises [Member]",
        "terseLabel": "U.S. government/sponsored agency \u2013 Residential"
       }
      }
     },
     "localname": "ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_RestrictedCashAndDueFromBanks": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Restricted Cash And Due From Banks.",
        "label": "Restricted Cash And Due From Banks",
        "terseLabel": "Cash and interest bearing deposits, restricted",
        "verboseLabel": "Cash and due from banks, restricted"
       }
      }
     },
     "localname": "RestrictedCashAndDueFromBanks",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnauditedParenthetical"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_RestrictedInterestBearingDepositsInBanks": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Restricted interest bearing deposits in banks.",
        "label": "Restricted Interest Bearing Deposits In Banks",
        "terseLabel": "Restricted interest-bearing deposits"
       }
      }
     },
     "localname": "RestrictedInterestBearingDepositsInBanks",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnauditedParenthetical"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_RevolvingCreditFacilityNotLetterofCreditMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Revolving Credit Facility, Not Letter of Credit [Member]",
        "label": "Revolving Credit Facility Not Letterof Credit [Member]",
        "terseLabel": "Revolving Credit Facility, Not Letter of Credit"
       }
      }
     },
     "localname": "RevolvingCreditFacilityNotLetterofCreditMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_RiskWeightedAssetsIncludingOffBalanceSheetItems": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Risk weighted assets including off balance sheet items.",
        "label": "Risk Weighted Assets Including Off Balance Sheet Items",
        "terseLabel": "Risk-Weighted Assets"
       }
      }
     },
     "localname": "RiskWeightedAssetsIncludingOffBalanceSheetItems",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_SalesTypeAndDirectFinancingLeasesVariableLeaseIncome": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails": {
       "order": 10030.0,
       "parentTag": "cit_LeaseIncomeIncludingIncomeOnLeverageLeases",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sales-type and direct financing leases, variable lease income.",
        "label": "Sales Type And Direct Financing Leases Variable Lease Income",
        "terseLabel": "Variable lease income included in Other non-interest income"
       }
      }
     },
     "localname": "SalesTypeAndDirectFinancingLeasesVariableLeaseIncome",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_ScheduleOfAvailableForSaleAndHeldToMaturitySecuritiesLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule of available for sale and held to maturity securities.",
        "label": "Schedule Of Available For Sale And Held To Maturity Securities [Line Items]",
        "terseLabel": "Schedule Of Available For Sale And Held To Maturity Securities [Line Items]"
       }
      }
     },
     "localname": "ScheduleOfAvailableForSaleAndHeldToMaturitySecuritiesLineItems",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_ScheduleOfAvailableForSaleAndHeldToMaturitySecuritiesTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule of available for sale and held to maturity securities.",
        "label": "Schedule Of Available For Sale And Held To Maturity Securities [Table]",
        "terseLabel": "Schedule Of Available For Sale And Held To Maturity Securities [Table]"
       }
      }
     },
     "localname": "ScheduleOfAvailableForSaleAndHeldToMaturitySecuritiesTable",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_ScheduleOfContractualMaturitiesOfTimeDeposits100000OrMoreTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule Of Contractual Maturities Of Time Deposits 100000 Or More [Table Text Block]",
        "label": "Schedule Of Contractual Maturities Of Time Deposits100000 Or More Table [Text Block]",
        "terseLabel": "Schedule of Certificates of Deposit $100 Thousand or More"
       }
      }
     },
     "localname": "ScheduleOfContractualMaturitiesOfTimeDeposits100000OrMoreTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_ScheduleOfCumulativeFairValueHedgingAdjustmentsTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule Of Cumulative Fair Value Hedging Adjustments.",
        "label": "Schedule Of Cumulative Fair Value Hedging Adjustments Table [Text Block]",
        "terseLabel": "Carrying Value of Hedged Items and Associated Cumulative Hedging Adjustment Relating for Fair Value Hedges"
       }
      }
     },
     "localname": "ScheduleOfCumulativeFairValueHedgingAdjustmentsTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_ScheduleOfFinanceReceivablesTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule of finance receivables.",
        "label": "Schedule Of Finance Receivables Table [Text Block]",
        "terseLabel": "Schedule of Loans by Product"
       }
      }
     },
     "localname": "ScheduleOfFinanceReceivablesTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_ScheduleOfLoansInProcessOfForeclosureTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule of loans in process of foreclosure.",
        "label": "Schedule Of Loans In Process Of Foreclosure [Table]",
        "terseLabel": "Schedule Of Loans In Process Of Foreclosure [Table]"
       }
      }
     },
     "localname": "ScheduleOfLoansInProcessOfForeclosureTable",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansInProcessOfForeclosureParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_ScheduleOfLoansInProcessOfForeclosureTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule of loans in process of foreclosure.",
        "label": "Schedule Of Loans In Process Of Foreclosure Table [Text Block]",
        "terseLabel": "Schedule of Loans in Process of Foreclosure"
       }
      }
     },
     "localname": "ScheduleOfLoansInProcessOfForeclosureTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_ScheduleOfSegmentLoansAndLeasesHeldForInvestmentBasedOnObligorLocationTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule of segment loans and leases held for investment based on obligor location.",
        "label": "Schedule Of Segment Loans And Leases Held For Investment Based On Obligor Location Table [Text Block]",
        "terseLabel": "Schedule Of Loans By Segment, Based On Obligor Location"
       }
      }
     },
     "localname": "ScheduleOfSegmentLoansAndLeasesHeldForInvestmentBasedOnObligorLocationTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_SecuritiesSoldUnderAgreementToRepurchaseMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Securities sold under agreement to repurchase.",
        "label": "Securities Sold Under Agreement To Repurchase [Member]",
        "terseLabel": "Securities sold under agreement to repurchase"
       }
      }
     },
     "localname": "SecuritiesSoldUnderAgreementToRepurchaseMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_SmallCommercialLoansMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Small Commercial Loans [Member]",
        "label": "Small Commercial Loans [Member]",
        "terseLabel": "Small Commercial Loans"
       }
      }
     },
     "localname": "SmallCommercialLoansMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_StandbyLettersOfCredit": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Standby letters of credit",
        "label": "Standby Letters Of Credit",
        "totalLabel": "Standby letters of credit - Total Outstanding"
       }
      }
     },
     "localname": "StandbyLettersOfCredit",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_StandbyLettersOfCreditCurrent": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10090.0,
       "parentTag": "cit_StandbyLettersOfCredit",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Standby letters of credit current",
        "label": "Standby Letters Of Credit Current",
        "terseLabel": "Standby letters of credit - Due to Expire Within One Year"
       }
      }
     },
     "localname": "StandbyLettersOfCreditCurrent",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_StandbyLettersOfCreditNoncurrent": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails": {
       "order": 10100.0,
       "parentTag": "cit_StandbyLettersOfCredit",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Standby letters of credit noncurrent",
        "label": "Standby Letters Of Credit Noncurrent",
        "terseLabel": "Standby letters of credit - Due to Expire After One Year"
       }
      }
     },
     "localname": "StandbyLettersOfCreditNoncurrent",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsSummaryOfCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_SummaryOfKeyValuationInputAssumptionsTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Summary of key valuation input assumptions.",
        "label": "Summary Of Key Valuation Input Assumptions Table [Text Block]",
        "terseLabel": "Summary of Key Valuation Input Assumptions by Division"
       }
      }
     },
     "localname": "SummaryOfKeyValuationInputAssumptionsTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_SummaryOfLoanValuationsByDivisionInEachSegmentTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Summary of loan valuations by division in each segment.",
        "label": "Summary Of Loan Valuations By Division In Each Segment Table [Text Block]",
        "terseLabel": "Summary of Loan Valuations by Division in Each Segment"
       }
      }
     },
     "localname": "SummaryOfLoanValuationsByDivisionInEachSegmentTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_SummaryOfOffBalanceSheetCreditRelatedCommitmentsAsWellAsPurchaseAndFundingCommitmentsTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Summary of off balance sheet credit related commitments as well as purchase and funding commitments.",
        "label": "Summary Of Off Balance Sheet Credit Related Commitments As Well As Purchase And Funding Commitments Table [Text Block]",
        "terseLabel": "Summary of Commitments"
       }
      }
     },
     "localname": "SummaryOfOffBalanceSheetCreditRelatedCommitmentsAsWellAsPurchaseAndFundingCommitmentsTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_SupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Supplemental balance sheet and cash flow information related to leases.",
        "label": "Supplemental Balance Sheet And Cash Flow Information Related To Leases Table [Text Block]",
        "terseLabel": "Schedule of Supplemental Balance Sheet and Cash Flow Information Related to Leases"
       }
      }
     },
     "localname": "SupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesTableTextBlock",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "cit_SupranationalSecuritiesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Supranational Securities [Member]",
        "label": "Supranational Securities [Member]",
        "terseLabel": "Supranational securities"
       }
      }
     },
     "localname": "SupranationalSecuritiesMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_TaxCreditEquityInvestmentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tax Credit Equity Investment [Member]",
        "label": "Tax Credit Equity Investment [Member]",
        "terseLabel": "Tax credit equity investments"
       }
      }
     },
     "localname": "TaxCreditEquityInvestmentMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_TaxCreditInvestmentsFairValueDisclosure": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails": {
       "order": 10040.0,
       "parentTag": "us-gaap_AssetsFairValueDisclosure",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tax credit investments fair value disclosure.",
        "label": "Tax Credit Investments Fair Value Disclosure",
        "terseLabel": "Tax credit investments"
       }
      }
     },
     "localname": "TaxCreditInvestmentsFairValueDisclosure",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_Tier1CapitalRatioMinimumStated": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tier 1 capital ratio minimum stated.",
        "label": "Tier1 Capital Ratio Minimum Stated",
        "terseLabel": "Tier 1 capital ratio, minimum stated"
       }
      }
     },
     "localname": "Tier1CapitalRatioMinimumStated",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsParentheticalDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_TotalCapitalRatioMinimumStated": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total capital ratio minimum stated.",
        "label": "Total Capital Ratio Minimum Stated",
        "terseLabel": "Total capital ratio, minimum stated"
       }
      }
     },
     "localname": "TotalCapitalRatioMinimumStated",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsParentheticalDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_TotalNonPerformingAssets": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total non performing assets.",
        "label": "Total Non Performing Assets",
        "totalLabel": "Total non-performing assets"
       }
      }
     },
     "localname": "TotalNonPerformingAssets",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_TotalTierOneCapitalAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total tier one capital.",
        "label": "Total Tier One Capital [Abstract]",
        "terseLabel": "Total Capital Ratio:"
       }
      }
     },
     "localname": "TotalTierOneCapitalAbstract",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "cit_TransferOfAssetsFromHeldForInvestmentToOreo": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Transfer of assets from held for investment to OREO",
        "label": "Transfer Of Assets From Held For Investment To Oreo",
        "terseLabel": "Transfers of assets to OREO"
       }
      }
     },
     "localname": "TransferOfAssetsFromHeldForInvestmentToOreo",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_TransitionRuleToImplementCurrentExpectedCreditLossesOptionToDelayTerm": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Transition rule to implement current expected credit losses option to delay term.",
        "label": "Transition Rule To Implement Current Expected Credit Losses Option To Delay Term",
        "terseLabel": "Option to delay term"
       }
      }
     },
     "localname": "TransitionRuleToImplementCurrentExpectedCreditLossesOptionToDelayTerm",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "cit_TransitionRuleToImplementCurrentExpectedCreditLossesTransitionPeriod": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Transition rule to implement current expected credit losses transition period.",
        "label": "Transition Rule To Implement Current Expected Credit Losses Transition Period",
        "terseLabel": "Transition period"
       }
      }
     },
     "localname": "TransitionRuleToImplementCurrentExpectedCreditLossesTransitionPeriod",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "cit_TransitionRuleToImplementCurrentExpectedCreditLossesTransitionPeriodStartDate": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Transition rule to implement current expected credit losses transition period start date.",
        "label": "Transition Rule To Implement Current Expected Credit Losses Transition Period Start Date",
        "terseLabel": "Transition period start date"
       }
      }
     },
     "localname": "TransitionRuleToImplementCurrentExpectedCreditLossesTransitionPeriodStartDate",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "dateItemType"
    },
    "cit_TroubledDebtRestructuringCovenantReliefRateOther": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Troubled debt restructuring, covenant relief rate other.",
        "label": "Troubled Debt Restructuring Covenant Relief Rate Other",
        "terseLabel": "Troubled debt restructuring, covenant relief rate, other (percentage)"
       }
      }
     },
     "localname": "TroubledDebtRestructuringCovenantReliefRateOther",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_TroubledDebtRestructuringPaymentDeferralRate": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Troubled debt restructuring, payment deferral rate.",
        "label": "Troubled Debt Restructuring Payment Deferral Rate",
        "terseLabel": "Troubled debt restructuring, payment deferral rate (percentage)"
       }
      }
     },
     "localname": "TroubledDebtRestructuringPaymentDeferralRate",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "cit_UnamortizedLoanCommitmentAndUnamortizedPremiumsAndDiscounts": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Unamortized loan commitment and unamortized premiums and discounts.",
        "label": "Unamortized Loan Commitment And Unamortized Premiums And Discounts",
        "terseLabel": "Unamortized premiums / (discounts)"
       }
      }
     },
     "localname": "UnamortizedLoanCommitmentAndUnamortizedPremiumsAndDiscounts",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansComponentsOfNetInvestmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_UnconsolidatedVariableInterestEntitiesViesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Unconsolidated Variable Interest Entities (VIEs) [Member]",
        "label": "Unconsolidated Variable Interest Entities Vies [Member]",
        "terseLabel": "Unconsolidated Variable Interest Entities (VIEs)"
       }
      }
     },
     "localname": "UnconsolidatedVariableInterestEntitiesViesMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "cit_UnearnedIncome": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Unearned income.",
        "label": "Unearned Income",
        "negatedLabel": "Unearned income"
       }
      }
     },
     "localname": "UnearnedIncome",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansComponentsOfNetInvestmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "cit_ValuationTechniqueInternalValuationModelMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Valuation technique internal valuation model.",
        "label": "Valuation Technique Internal Valuation Model [Member]",
        "terseLabel": "Internal Valuation Model"
       }
      }
     },
     "localname": "ValuationTechniqueInternalValuationModelMember",
     "nsuri": "http://www.cit.com/20200331",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "dei_AmendmentFlag": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.",
        "label": "Amendment Flag",
        "terseLabel": "Amendment Flag"
       }
      }
     },
     "localname": "AmendmentFlag",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_CityAreaCode": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Area code of city",
        "label": "City Area Code",
        "terseLabel": "City Area Code"
       }
      }
     },
     "localname": "CityAreaCode",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_CoverAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Cover page.",
        "label": "Cover [Abstract]"
       }
      }
     },
     "localname": "CoverAbstract",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "dei_CurrentFiscalYearEndDate": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "End date of current fiscal year in the format --MM-DD.",
        "label": "Current Fiscal Year End Date",
        "terseLabel": "Current Fiscal Year End Date"
       }
      }
     },
     "localname": "CurrentFiscalYearEndDate",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "gMonthDayItemType"
    },
    "dei_DocumentFiscalPeriodFocus": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fiscal period values are FY, Q1, Q2, and Q3.  1st, 2nd and 3rd quarter 10-Q or 10-QT statements have value Q1, Q2, and Q3 respectively, with 10-K, 10-KT or other fiscal year statements having FY.",
        "label": "Document Fiscal Period Focus",
        "terseLabel": "Document Fiscal Period Focus"
       }
      }
     },
     "localname": "DocumentFiscalPeriodFocus",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "fiscalPeriodItemType"
    },
    "dei_DocumentFiscalYearFocus": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This is focus fiscal year of the document report in CCYY format. For a 2006 annual report, which may also provide financial information from prior periods, fiscal 2006 should be given as the fiscal year focus. Example: 2006.",
        "label": "Document Fiscal Year Focus",
        "terseLabel": "Document Fiscal Year Focus"
       }
      }
     },
     "localname": "DocumentFiscalYearFocus",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "gYearItemType"
    },
    "dei_DocumentInformationLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Document Information [Line Items]",
        "terseLabel": "Document Information [Line Items]"
       }
      }
     },
     "localname": "DocumentInformationLineItems",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "stringItemType"
    },
    "dei_DocumentInformationTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Container to support the formal attachment of each official or unofficial, public or private document as part of a submission package.",
        "label": "Document Information [Table]",
        "terseLabel": "Document Information [Table]"
       }
      }
     },
     "localname": "DocumentInformationTable",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "stringItemType"
    },
    "dei_DocumentPeriodEndDate": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented.  If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.",
        "label": "Document Period End Date",
        "terseLabel": "Document Period End Date"
       }
      }
     },
     "localname": "DocumentPeriodEndDate",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "dateItemType"
    },
    "dei_DocumentQuarterlyReport": {
     "auth_ref": [
      "r543"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Boolean flag that is true only for a form used as an quarterly report.",
        "label": "Document Quarterly Report",
        "terseLabel": "Document Quarterly Report"
       }
      }
     },
     "localname": "DocumentQuarterlyReport",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_DocumentTransitionReport": {
     "auth_ref": [
      "r544"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Boolean flag that is true only for a form used as a transition report.",
        "label": "Document Transition Report",
        "terseLabel": "Document Transition Report"
       }
      }
     },
     "localname": "DocumentTransitionReport",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_DocumentType": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.",
        "label": "Document Type",
        "terseLabel": "Document Type"
       }
      }
     },
     "localname": "DocumentType",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "submissionTypeItemType"
    },
    "dei_EntityAddressAddressLine1": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Address Line 1 such as Attn, Building Name, Street Name",
        "label": "Entity Address Address Line1",
        "terseLabel": "Entity Address, Address Line One"
       }
      }
     },
     "localname": "EntityAddressAddressLine1",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityAddressCityOrTown": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Name of the City or Town",
        "label": "Entity Address City Or Town",
        "terseLabel": "Entity Address, City or Town"
       }
      }
     },
     "localname": "EntityAddressCityOrTown",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityAddressPostalZipCode": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Code for the postal or zip code",
        "label": "Entity Address Postal Zip Code",
        "terseLabel": "Entity Address, Postal Zip Code"
       }
      }
     },
     "localname": "EntityAddressPostalZipCode",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityAddressStateOrProvince": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Name of the state or province.",
        "label": "Entity Address State Or Province",
        "terseLabel": "Entity Address, State or Province"
       }
      }
     },
     "localname": "EntityAddressStateOrProvince",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "stateOrProvinceItemType"
    },
    "dei_EntityCentralIndexKey": {
     "auth_ref": [
      "r546"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.",
        "label": "Entity Central Index Key",
        "terseLabel": "Entity Central Index Key"
       }
      }
     },
     "localname": "EntityCentralIndexKey",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "centralIndexKeyItemType"
    },
    "dei_EntityCommonStockSharesOutstanding": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Indicate number of shares or other units outstanding of each of registrant's classes of capital or common stock or other ownership interests, if and as stated on cover of related periodic report. Where multiple classes or units exist define each class/interest by adding class of stock items such as Common Class A [Member], Common Class B [Member] or Partnership Interest [Member] onto the Instrument [Domain] of the Entity Listings, Instrument.",
        "label": "Entity Common Stock Shares Outstanding",
        "terseLabel": "Entity Common Stock, Shares Outstanding"
       }
      }
     },
     "localname": "EntityCommonStockSharesOutstanding",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "sharesItemType"
    },
    "dei_EntityCurrentReportingStatus": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Indicate 'Yes' or 'No' whether registrants (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that registrants were required to file such reports), and (2) have been subject to such filing requirements for the past 90 days. This information should be based on the registrant's current or most recent filing containing the related disclosure.",
        "label": "Entity Current Reporting Status",
        "terseLabel": "Entity Current Reporting Status"
       }
      }
     },
     "localname": "EntityCurrentReportingStatus",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "All the names of the entities being reported upon in a document. Any legal structure used to conduct activities or to hold assets. Some examples of such structures are corporations, partnerships, limited liability companies, grantor trusts, and other trusts. This item does not include business and geographical segments which are included in the geographical or business segments domains.",
        "label": "Entity [Domain]",
        "terseLabel": "Entity"
       }
      }
     },
     "localname": "EntityDomain",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "dei_EntityEmergingGrowthCompany": {
     "auth_ref": [
      "r546"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Indicate if registrant meets the emerging growth company criteria.",
        "label": "Entity Emerging Growth Company",
        "terseLabel": "Entity Emerging Growth Company"
       }
      }
     },
     "localname": "EntityEmergingGrowthCompany",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntityFileNumber": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.",
        "label": "Entity File Number",
        "terseLabel": "Entity File Number"
       }
      }
     },
     "localname": "EntityFileNumber",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "fileNumberItemType"
    },
    "dei_EntityFilerCategory": {
     "auth_ref": [
      "r546"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Indicate whether the registrant is one of the following: Large Accelerated Filer, Accelerated Filer, Non-accelerated Filer. Definitions of these categories are stated in Rule 12b-2 of the Exchange Act. This information should be based on the registrant's current or most recent filing containing the related disclosure.",
        "label": "Entity Filer Category",
        "terseLabel": "Entity Filer Category"
       }
      }
     },
     "localname": "EntityFilerCategory",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "filerCategoryItemType"
    },
    "dei_EntityIncorporationStateCountryCode": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Two-character EDGAR code representing the state or country of incorporation.",
        "label": "Entity Incorporation State Country Code",
        "terseLabel": "Entity Incorporation, State or Country Code"
       }
      }
     },
     "localname": "EntityIncorporationStateCountryCode",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "edgarStateCountryItemType"
    },
    "dei_EntityInteractiveDataCurrent": {
     "auth_ref": [
      "r547"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Boolean flag that is true when the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).",
        "label": "Entity Interactive Data Current",
        "terseLabel": "Entity Interactive Data Current"
       }
      }
     },
     "localname": "EntityInteractiveDataCurrent",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityRegistrantName": {
     "auth_ref": [
      "r546"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.",
        "label": "Entity Registrant Name",
        "terseLabel": "Entity Registrant Name"
       }
      }
     },
     "localname": "EntityRegistrantName",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityShellCompany": {
     "auth_ref": [
      "r546"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Boolean flag that is true when the registrant is a shell company as defined in Rule 12b-2 of the Exchange Act.",
        "label": "Entity Shell Company",
        "terseLabel": "Entity Shell Company"
       }
      }
     },
     "localname": "EntityShellCompany",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntitySmallBusiness": {
     "auth_ref": [
      "r546"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Indicates that the company is a Smaller Reporting Company (SRC).",
        "label": "Entity Small Business",
        "terseLabel": "Entity Small Business"
       }
      }
     },
     "localname": "EntitySmallBusiness",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntityTaxIdentificationNumber": {
     "auth_ref": [
      "r546"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.",
        "label": "Entity Tax Identification Number",
        "terseLabel": "Entity Tax Identification Number"
       }
      }
     },
     "localname": "EntityTaxIdentificationNumber",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "employerIdItemType"
    },
    "dei_LegalEntityAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The set of legal entities associated with a report.",
        "label": "Legal Entity [Axis]",
        "terseLabel": "Legal Entity"
       }
      }
     },
     "localname": "LegalEntityAxis",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "dei_LocalPhoneNumber": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Local phone number for entity.",
        "label": "Local Phone Number",
        "terseLabel": "Local Phone Number"
       }
      }
     },
     "localname": "LocalPhoneNumber",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_Security12bTitle": {
     "auth_ref": [
      "r541"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Title of a 12(b) registered security.",
        "label": "Security12b Title",
        "terseLabel": "Title of 12(b) Security"
       }
      }
     },
     "localname": "Security12bTitle",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "securityTitleItemType"
    },
    "dei_SecurityExchangeName": {
     "auth_ref": [
      "r542"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Name of the Exchange on which a security is registered.",
        "label": "Security Exchange Name",
        "terseLabel": "Security Exchange Name"
       }
      }
     },
     "localname": "SecurityExchangeName",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "edgarExchangeCodeItemType"
    },
    "dei_TradingSymbol": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Trading symbol of an instrument as listed on an exchange.",
        "label": "Trading Symbol",
        "terseLabel": "Trading Symbol"
       }
      }
     },
     "localname": "TradingSymbol",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "tradingSymbolItemType"
    },
    "srt_ConsolidatedEntitiesAxis": {
     "auth_ref": [
      "r540"
     ],
     "lang": {
      "en-US": {
       "role": {
        "label": "Consolidated Entities [Axis]",
        "terseLabel": "Consolidated Entities"
       }
      }
     },
     "localname": "ConsolidatedEntitiesAxis",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_ConsolidatedEntitiesDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Consolidated Entities [Domain]",
        "terseLabel": "Consolidated Entities"
       }
      }
     },
     "localname": "ConsolidatedEntitiesDomain",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_ConsolidationItemsAxis": {
     "auth_ref": [
      "r134",
      "r140"
     ],
     "lang": {
      "en-US": {
       "role": {
        "label": "Consolidation Items [Axis]",
        "terseLabel": "Corporate"
       }
      }
     },
     "localname": "ConsolidationItemsAxis",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_ConsolidationItemsDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Consolidation Items [Domain]",
        "terseLabel": "Consolidation Items"
       }
      }
     },
     "localname": "ConsolidationItemsDomain",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_MaximumMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Maximum [Member]",
        "terseLabel": "Maximum"
       }
      }
     },
     "localname": "MaximumMember",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureContingenciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_MinimumMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Minimum [Member]",
        "terseLabel": "Minimum"
       }
      }
     },
     "localname": "MinimumMember",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureContingenciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_ParentCompanyMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Parent Company [Member]",
        "terseLabel": "CIT Group Inc."
       }
      }
     },
     "localname": "ParentCompanyMember",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_RangeAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Range [Axis]",
        "terseLabel": "Statistical Measurement"
       }
      }
     },
     "localname": "RangeAxis",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureContingenciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_RangeMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Range [Member]",
        "terseLabel": "Statistical Measurement"
       }
      }
     },
     "localname": "RangeMember",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureContingenciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_RegulatoryCapitalRequirementsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Regulatory Capital Requirements [Abstract]"
       }
      }
     },
     "localname": "RegulatoryCapitalRequirementsAbstract",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "srt_SubsidiariesMember": {
     "auth_ref": [
      "r314",
      "r436",
      "r437"
     ],
     "lang": {
      "en-US": {
       "role": {
        "label": "Subsidiaries [Member]",
        "terseLabel": "Subsidiaries",
        "verboseLabel": "CIT-owned Subsidiaries"
       }
      }
     },
     "localname": "SubsidiariesMember",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_WeightedAverageMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Weighted Average [Member]",
        "terseLabel": "Weighted Avg.",
        "verboseLabel": "Weighted Avg."
       }
      }
     },
     "localname": "WeightedAverageMember",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccountingPoliciesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Accounting Policies [Abstract]"
       }
      }
     },
     "localname": "AccountingPoliciesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccountingStandardsUpdate201613Member": {
     "auth_ref": [
      "r206"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Accounting Standards Update 2016-13 Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.",
        "label": "Accounting Standards Update201613 [Member]",
        "terseLabel": "ASU 2016-13"
       }
      }
     },
     "localname": "AccountingStandardsUpdate201613Member",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccountsNotesAndLoansReceivableLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Accounts Notes And Loans Receivable [Line Items]",
        "terseLabel": "Accounts, Notes, Loans and Financing Receivable [Line Items]"
       }
      }
     },
     "localname": "AccountsNotesAndLoansReceivableLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfModificationsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfTdrsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis": {
     "auth_ref": [
      "r39"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of receivable.",
        "label": "Accounts Notes Loans And Financing Receivable By Receivable Type [Axis]",
        "terseLabel": "Receivable Type"
       }
      }
     },
     "localname": "AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember": {
     "auth_ref": [
      "r58",
      "r64",
      "r65",
      "r313",
      "r349"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Accumulated other comprehensive (income) loss related to defined benefit plans attributable to the parent.",
        "label": "Accumulated Defined Benefit Plans Adjustment [Member]",
        "terseLabel": "Changes in benefit plans net (loss) gains and prior service (cost)/credit",
        "verboseLabel": "Changes in benefit plan net loss and prior service (cost)/credit losses"
       }
      }
     },
     "localname": "AccumulatedDefinedBenefitPlansAdjustmentMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember": {
     "auth_ref": [
      "r54",
      "r55",
      "r57",
      "r64",
      "r65"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Accumulated unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), attributable to parent.",
        "label": "Accumulated Net Unrealized Investment Gain Loss [Member]",
        "terseLabel": "Unrealized net gains on securities AFS",
        "verboseLabel": "Unrealized net gains (losses) on AFS securities"
       }
      }
     },
     "localname": "AccumulatedNetUnrealizedInvestmentGainLossMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Accumulated Other Comprehensive Income Loss [Line Items]",
        "terseLabel": "Accumulated Other Comprehensive Income (Loss) [Line Items]"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeLossLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax": {
     "auth_ref": [
      "r61",
      "r63",
      "r64"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10080.0,
       "parentTag": "cit_CommonStockholdersEquityAttributableToParent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.",
        "label": "Accumulated Other Comprehensive Income Loss Net Of Tax",
        "terseLabel": "Accumulated other comprehensive income (loss)",
        "totalLabel": "Net Unrealized"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeLossNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]",
        "terseLabel": "Other comprehensive income, net of tax"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeLossTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about components of accumulated other comprehensive income (loss).",
        "label": "Accumulated Other Comprehensive Income Loss [Table]",
        "terseLabel": "Accumulated Other Comprehensive Income Loss [Table]"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeLossTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeMember": {
     "auth_ref": [
      "r60",
      "r64",
      "r65",
      "r349"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Accumulated increase (decrease) in equity from transactions and other events and circumstances from non-owner sources, attributable to the parent. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners.",
        "label": "Accumulated Other Comprehensive Income [Member]",
        "terseLabel": "Accumulated Other Comprehensive Income (Loss)",
        "verboseLabel": "Total AOCI"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccumulatedTranslationAdjustmentMember": {
     "auth_ref": [
      "r53",
      "r64",
      "r65",
      "r349"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Accumulated other comprehensive income (loss) resulting from foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature, attributable to the parent.",
        "label": "Accumulated Translation Adjustment [Member]",
        "terseLabel": "Foreign currency translation adjustments"
       }
      }
     },
     "localname": "AccumulatedTranslationAdjustmentMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AdditionalPaidInCapital": {
     "auth_ref": [
      "r26"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10060.0,
       "parentTag": "cit_CommonStockholdersEquityAttributableToParent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders. Includes adjustments to additional paid in capital. Some examples of such adjustments include recording the issuance of debt with a beneficial conversion feature and certain tax consequences of equity instruments awarded to employees. Use this element for the aggregate amount of additional paid-in capital associated with common and preferred stock. For additional paid-in capital associated with only common stock, use the element additional paid in capital, common stock. For additional paid-in capital associated with only preferred stock, use the element additional paid in capital, preferred stock.",
        "label": "Additional Paid In Capital",
        "terseLabel": "Paid-in capital"
       }
      }
     },
     "localname": "AdditionalPaidInCapital",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AdditionalPaidInCapitalMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders.",
        "label": "Additional Paid In Capital [Member]",
        "terseLabel": "Paid-in Capital"
       }
      }
     },
     "localname": "AdditionalPaidInCapitalMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AdjustmentsForNewAccountingPronouncementsAxis": {
     "auth_ref": [
      "r118"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by new accounting pronouncement.",
        "label": "Adjustments For New Accounting Pronouncements [Axis]",
        "terseLabel": "Adjustments for New Accounting Pronouncements"
       }
      }
     },
     "localname": "AdjustmentsForNewAccountingPronouncementsAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract]",
        "terseLabel": "Adjustments to reconcile net (loss) income to net cash flows from operations:"
       }
      }
     },
     "localname": "AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AdvancesFromFederalHomeLoanBanks": {
     "auth_ref": [
      "r493"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.",
        "label": "Advances From Federal Home Loan Banks",
        "terseLabel": "FHLB amount of advance"
       }
      }
     },
     "localname": "AdvancesFromFederalHomeLoanBanks",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AgencySecuritiesMember": {
     "auth_ref": [
      "r198"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Securities issued by government sponsored entities.",
        "label": "Agency Securities [Member]",
        "terseLabel": "Agency securities"
       }
      }
     },
     "localname": "AgencySecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock": {
     "auth_ref": [
      "r153",
      "r216"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of allowance for credit loss on financing receivable.",
        "label": "Allowance For Credit Losses On Financing Receivables Table [Text Block]",
        "terseLabel": "Schedule of Allowance for Credit Losses and Recorded Investment in Finance Receivables"
       }
      }
     },
     "localname": "AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_AllowanceForCreditLossesTextBlock": {
     "auth_ref": [
      "r182"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for allowance for credit losses.",
        "label": "Allowance For Credit Losses [Text Block]",
        "terseLabel": "ALLOWANCE FOR CREDIT LOSSES"
       }
      }
     },
     "localname": "AllowanceForCreditLossesTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLosses"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet": {
     "auth_ref": [
      "r160",
      "r467"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of other addition (reduction) in allowance reserve for credit loss.",
        "label": "Allowance For Loan And Lease Losses Adjustments Net",
        "terseLabel": "Other"
       }
      }
     },
     "localname": "AllowanceForLoanAndLeaseLossesAdjustmentsNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AlternativeInvestmentMeasurementInput": {
     "auth_ref": [
      "r396"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value of input used to measure alternative investment.",
        "label": "Alternative Investment Measurement Input",
        "terseLabel": "Fair value input rate"
       }
      }
     },
     "localname": "AlternativeInvestmentMeasurementInput",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "decimalItemType"
    },
    "us-gaap_AmortizationOfIntangibleAssets": {
     "auth_ref": [
      "r100",
      "r259",
      "r265"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.",
        "label": "Amortization Of Intangible Assets",
        "negatedLabel": "Amortization"
       }
      }
     },
     "localname": "AmortizationOfIntangibleAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AociBeforeTaxAttributableToParent": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before tax of increase (decrease) in accumulated equity from transactions and other events and circumstances from non-owner sources, attributable to parent. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners (distributions to owners).",
        "label": "Aoci Before Tax Attributable To Parent",
        "terseLabel": "Gross Unrealized"
       }
      }
     },
     "localname": "AociBeforeTaxAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AociTaxAttributableToParent": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of tax expense (benefit) allocated to accumulated other comprehensive income (loss) attributable to parent.",
        "label": "Aoci Tax Attributable To Parent",
        "negatedLabel": "Income Taxes"
       }
      }
     },
     "localname": "AociTaxAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AssetBackedSecuritiesMember": {
     "auth_ref": [
      "r195",
      "r311"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Securities that are primarily serviced by the cash flows of a discrete pool of receivables or other financial assets for example, but not limited to, credit card receivables, car loans, recreational vehicle loans, and mobile home loans.",
        "label": "Asset Backed Securities [Member]",
        "terseLabel": "Agency Asset-Backed Securities"
       }
      }
     },
     "localname": "AssetBackedSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AssetImpairmentCharges": {
     "auth_ref": [
      "r100",
      "r270"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10280.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.",
        "label": "Asset Impairment Charges",
        "terseLabel": "Goodwill impairment"
       }
      }
     },
     "localname": "AssetImpairmentCharges",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Assets": {
     "auth_ref": [
      "r137",
      "r451",
      "r515"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.",
        "label": "Assets",
        "totalLabel": "Total Assets"
       }
      }
     },
     "localname": "Assets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AssetsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Assets [Abstract]",
        "terseLabel": "Assets"
       }
      }
     },
     "localname": "AssetsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AssetsFairValueDisclosure": {
     "auth_ref": [
      "r391"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.",
        "label": "Assets Fair Value Disclosure",
        "terseLabel": "Estimated fair value - assets",
        "totalLabel": "Total Assets"
       }
      }
     },
     "localname": "AssetsFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure": {
     "auth_ref": [
      "r391"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_AssetsFairValueDisclosure",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of assets classified as held for sale.",
        "label": "Assets Held For Sale Long Lived Fair Value Disclosure",
        "terseLabel": "Assets held for sale",
        "verboseLabel": "Assets held for sale (excluding leases)"
       }
      }
     },
     "localname": "AssetsHeldForSaleLongLivedFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AssetsHeldForSaleNotPartOfDisposalGroup": {
     "auth_ref": [
      "r269"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10180.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of assets held-for-sale that are not part of a disposal group.",
        "label": "Assets Held For Sale Not Part Of Disposal Group",
        "terseLabel": "Assets held for sale"
       }
      }
     },
     "localname": "AssetsHeldForSaleNotPartOfDisposalGroup",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax": {
     "auth_ref": [
      "r188"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax",
        "terseLabel": "Debt securities, Unrealized Gains Gross"
       }
      }
     },
     "localname": "AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax": {
     "auth_ref": [
      "r189"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax",
        "negatedLabel": "Debt securities, Unrealized Losses Gross"
       }
      }
     },
     "localname": "AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis": {
     "auth_ref": [
      "r186",
      "r242"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Available For Sale Debt Securities Amortized Cost Basis",
        "totalLabel": "Debt securities, Amortized Cost"
       }
      }
     },
     "localname": "AvailableForSaleDebtSecuritiesAmortizedCostBasis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost": {
     "auth_ref": [
      "r193"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails": {
       "order": 10070.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth fiscal year through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost",
        "terseLabel": "After 5 through 10 years, Amortized Cost"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue": {
     "auth_ref": [
      "r190",
      "r193",
      "r488"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtSecurities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value",
        "terseLabel": "After 5 through 10 years, Fair value"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost": {
     "auth_ref": [
      "r192"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails": {
       "order": 10060.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost",
        "terseLabel": "After 1 through 5 years, Amortized Cost"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue": {
     "auth_ref": [
      "r190",
      "r192",
      "r487"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtSecurities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Available For Sale Securities Debt Maturities After One Through Five Years Fair Value",
        "terseLabel": "After 1 through 5 years, Fair Value"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost": {
     "auth_ref": [
      "r194"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails": {
       "order": 10080.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Available For Sale Securities Debt Maturities After Ten Years Amortized Cost",
        "terseLabel": "Due after 10 years, Amortized Cost"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue": {
     "auth_ref": [
      "r190",
      "r194",
      "r489"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails": {
       "order": 10040.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtSecurities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Available For Sale Securities Debt Maturities After Ten Years Fair Value",
        "terseLabel": "Due after 10 years, Fair Value"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost": {
     "auth_ref": [
      "r191"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails": {
       "order": 10050.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amortized cost of investment in debt security measured at fair value with change recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Available For Sale Securities Debt Maturities Within One Year Amortized Cost",
        "terseLabel": "Due in 1 year or less, Amortized Cost"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue": {
     "auth_ref": [
      "r190",
      "r191",
      "r486"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtSecurities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Available For Sale Securities Debt Maturities Within One Year Fair Value",
        "terseLabel": "Due in 1 year or less, Fair Value"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtSecurities": {
     "auth_ref": [
      "r184",
      "r187",
      "r242"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_AssetsFairValueDisclosure",
       "weight": 1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Available For Sale Securities Debt Securities",
        "terseLabel": "Debt securities, Fair Value",
        "totalLabel": "Total debt securities available-for-sale, Fair Value",
        "verboseLabel": "Debt securities"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtSecurities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableforsaleSecuritiesMember": {
     "auth_ref": [
      "r197"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Availableforsale Securities [Member]",
        "terseLabel": "Debt Securities \u2014 AFS",
        "verboseLabel": "Securities \u2014 AFS"
       }
      }
     },
     "localname": "AvailableforsaleSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_BalanceSheetLocationAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by location on balance sheet (statement of financial position).",
        "label": "Balance Sheet Location [Axis]",
        "terseLabel": "Balance Sheet Location"
       }
      }
     },
     "localname": "BalanceSheetLocationAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_BalanceSheetLocationDomain": {
     "auth_ref": [
      "r368",
      "r373"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Location in the balance sheet (statement of financial position).",
        "label": "Balance Sheet Location [Domain]",
        "terseLabel": "Balance Sheet Location"
       }
      }
     },
     "localname": "BalanceSheetLocationDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_BankOwnedLifeInsurance": {
     "auth_ref": [
      "r460"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10210.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The carrying amount of a life insurance policy on an officer, executive or employee for which the reporting entity (a bank) is entitled to proceeds from the policy upon death of the insured or surrender of the insurance policy.",
        "label": "Bank Owned Life Insurance",
        "terseLabel": "Bank-owned life insurance"
       }
      }
     },
     "localname": "BankOwnedLifeInsurance",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BaseRateMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Minimum rate investor will accept.",
        "label": "Base Rate [Member]",
        "terseLabel": "Base Rate"
       }
      }
     },
     "localname": "BaseRateMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_BasisOfAccountingPolicyPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy for basis of accounting, or basis of presentation, used to prepare the financial statements (for example, US Generally Accepted Accounting Principles, Other Comprehensive Basis of Accounting, IFRS).",
        "label": "Basis Of Accounting Policy Policy [Text Block]",
        "terseLabel": "Basis of Financial Information"
       }
      }
     },
     "localname": "BasisOfAccountingPolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_BusinessAcquisitionAcquireeDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Identification of the acquiree in a material business combination (or series of individually immaterial business combinations), which may include the name or other type of identification of the acquiree.",
        "label": "Business Acquisition Acquiree [Domain]",
        "terseLabel": "Business Acquisition, Acquiree"
       }
      }
     },
     "localname": "BusinessAcquisitionAcquireeDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSelectedUnauditedProFormaFinancialInformationDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_BusinessAcquisitionAxis": {
     "auth_ref": [
      "r329",
      "r330"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by business combination or series of individually immaterial business combinations.",
        "label": "Business Acquisition [Axis]",
        "terseLabel": "Business Acquisition"
       }
      }
     },
     "localname": "BusinessAcquisitionAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSelectedUnauditedProFormaFinancialInformationDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned": {
     "auth_ref": [
      "r341"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity.",
        "label": "Business Acquisition Equity Interest Issued Or Issuable Value Assigned",
        "terseLabel": "Business combination, value of shares issued"
       }
      }
     },
     "localname": "BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued": {
     "auth_ref": [
      "r341"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of shares of equity interests issued or issuable to acquire entity.",
        "label": "Business Acquisition Equity Interests Issued Or Issuable Number Of Shares Issued",
        "terseLabel": "Business combination, number of shares issued",
        "verboseLabel": "Number of shares issued"
       }
      }
     },
     "localname": "BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityNarrativeDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_BusinessAcquisitionLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Business Acquisition [Line Items]",
        "terseLabel": "Business Acquisition [Line Items]"
       }
      }
     },
     "localname": "BusinessAcquisitionLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSelectedUnauditedProFormaFinancialInformationDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired": {
     "auth_ref": [
      "r326"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage of voting equity interests acquired at the acquisition date in the business combination.",
        "label": "Business Acquisition Percentage Of Voting Interests Acquired",
        "terseLabel": "Business combination, percentage of outstanding shares of common stock"
       }
      }
     },
     "localname": "BusinessAcquisitionPercentageOfVotingInterestsAcquired",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_BusinessAcquisitionProFormaInformationTextBlock": {
     "auth_ref": [
      "r327",
      "r328"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of pro forma results of operations for a material business acquisition or series of individually immaterial business acquisitions that are material in the aggregate.",
        "label": "Business Acquisition Pro Forma Information [Text Block]",
        "terseLabel": "Selected Unaudited Pro Forma Financial Information"
       }
      }
     },
     "localname": "BusinessAcquisitionProFormaInformationTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss": {
     "auth_ref": [
      "r327",
      "r328"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.",
        "label": "Business Acquisitions Pro Forma Net Income Loss",
        "terseLabel": "Net (loss) income"
       }
      }
     },
     "localname": "BusinessAcquisitionsProFormaNetIncomeLoss",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSelectedUnauditedProFormaFinancialInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationAcquiredReceivablesFairValue": {
     "auth_ref": [
      "r332"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": 10090.0,
       "parentTag": "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of acquired receivable from business combination, excluding certain loans and debt securities acquired in transfer.",
        "label": "Business Combination Acquired Receivables Fair Value",
        "positiveLabel": "Fair value of loans",
        "terseLabel": "Loans"
       }
      }
     },
     "localname": "BusinessCombinationAcquiredReceivablesFairValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationConsiderationTransferred1": {
     "auth_ref": [
      "r337",
      "r338",
      "r339"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.",
        "label": "Business Combination Consideration Transferred1",
        "terseLabel": "Consideration paid",
        "verboseLabel": "Purchase price of acquisition"
       }
      }
     },
     "localname": "BusinessCombinationConsiderationTransferred1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationIntegrationRelatedCosts": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.",
        "label": "Business Combination Integration Related Costs",
        "terseLabel": "Integration costs"
       }
      }
     },
     "localname": "BusinessCombinationIntegrationRelatedCosts",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets": {
     "auth_ref": [
      "r333"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of assets acquired at the acquisition date.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Assets",
        "totalLabel": "Total assets"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Assets [Abstract]",
        "terseLabel": "Assets"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents": {
     "auth_ref": [
      "r333"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": 10070.0,
       "parentTag": "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Cash And Equivalents",
        "terseLabel": "Cash and interest-bearing cash"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities": {
     "auth_ref": [
      "r333"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": 10080.0,
       "parentTag": "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Assets Marketable Securities",
        "terseLabel": "Investment securities"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill": {
     "auth_ref": [
      "r333"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of intangible assets, excluding goodwill, acquired at the acquisition date.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Intangible Assets Other Than Goodwill",
        "terseLabel": "Intangible assets"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities": {
     "auth_ref": [
      "r333"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of liabilities assumed at the acquisition date.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Liabilities",
        "terseLabel": "Assumed liabilities",
        "totalLabel": "Total liabilities"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Liabilities [Abstract]",
        "terseLabel": "Liabilities"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet": {
     "auth_ref": [
      "r331",
      "r333"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Net",
        "totalLabel": "Total fair value of identifiable net assets"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Net [Abstract]",
        "terseLabel": "Recognized amounts of identifiable assets acquired and liabilities assumed, at fair value"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt": {
     "auth_ref": [
      "r333"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": 10060.0,
       "parentTag": "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of long-term debt due after one year or the normal operating cycle, if longer, assumed at the acquisition date.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Noncurrent Liabilities Long Term Debt",
        "terseLabel": "Borrowings",
        "verboseLabel": "Federal Home Loan Bank advances"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther": {
     "auth_ref": [
      "r333"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": 10050.0,
       "parentTag": "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of other liabilities due after one year or the normal operating cycle, if longer, assumed at the acquisition date.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Noncurrent Liabilities Other",
        "terseLabel": "Other liabilities"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets": {
     "auth_ref": [
      "r333"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails": {
       "order": 10100.0,
       "parentTag": "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of other assets expected to be realized or consumed after one year or the normal operating cycle, if longer, acquired at the acquisition date.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Other Noncurrent Assets",
        "terseLabel": "Other assets",
        "verboseLabel": "Other assets"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment": {
     "auth_ref": [
      "r331",
      "r333"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of property, plant, and equipment recognized as of the acquisition date.",
        "label": "Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Property Plant And Equipment",
        "terseLabel": "Property, furniture and fixtures"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet": {
     "auth_ref": [
      "r333"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.",
        "label": "Business Combination Recognized Identifiable Assets Acquired Goodwill And Liabilities Assumed Net",
        "terseLabel": "Assets acquired"
       }
      }
     },
     "localname": "BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BusinessCombinationsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Business Combinations [Abstract]"
       }
      }
     },
     "localname": "BusinessCombinationsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_Capital": {
     "auth_ref": [
      "r508",
      "r509",
      "r535",
      "r536"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of total capital as defined in the regulations.",
        "label": "Capital",
        "terseLabel": "Total Capital"
       }
      }
     },
     "localname": "Capital",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets": {
     "auth_ref": [
      "r499",
      "r502",
      "r509"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.",
        "label": "Capital Required For Capital Adequacy To Risk Weighted Assets",
        "terseLabel": "Effective minimum ratios under Basel III guidelines"
       }
      }
     },
     "localname": "CapitalRequiredForCapitalAdequacyToRiskWeightedAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets": {
     "auth_ref": [
      "r499"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as \"well capitalized\", in the regulatory framework for prompt corrective action.",
        "label": "Capital Required To Be Well Capitalized To Risk Weighted Assets",
        "terseLabel": "BHC and PCA Well-Capitalized"
       }
      }
     },
     "localname": "CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_CapitalToRiskWeightedAssets": {
     "auth_ref": [
      "r499",
      "r509"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total Capital divided by risk weighted assets as defined in the regulations.",
        "label": "Capital To Risk Weighted Assets",
        "terseLabel": "Actual"
       }
      }
     },
     "localname": "CapitalToRiskWeightedAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_CarryingReportedAmountFairValueDisclosureMember": {
     "auth_ref": [
      "r410",
      "r411"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measured as reported on the statement of financial position (balance sheet).",
        "label": "Carrying Reported Amount Fair Value Disclosure [Member]",
        "terseLabel": "Carrying Value"
       }
      }
     },
     "localname": "CarryingReportedAmountFairValueDisclosureMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations": {
     "auth_ref": [
      "r96",
      "r102",
      "r108"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnauditedParenthetical": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including, but not limited to, disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.",
        "label": "Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations",
        "periodEndLabel": "Cash, cash equivalents, and restricted cash end of period",
        "periodStartLabel": "Cash, cash equivalents, and restricted cash beginning of period",
        "totalLabel": "Total cash, cash equivalents, and restricted cash shown in the Statements of Cash Flows"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnauditedParenthetical"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect": {
     "auth_ref": [
      "r96",
      "r413"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase (decrease) in cash, cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including effect from exchange rate change. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.",
        "label": "Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect",
        "totalLabel": "Increase (decrease) in cash, cash equivalents and restricted cash"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Cash Flow Noncash Investing And Financing Activities Disclosure [Abstract]",
        "terseLabel": "Supplementary Non Cash Flow Disclosure"
       }
      }
     },
     "localname": "CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations": {
     "auth_ref": [
      "r12",
      "r96"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash inflow (outflow) of investing activities of discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.",
        "label": "Cash Provided By Used In Investing Activities Discontinued Operations",
        "terseLabel": "Net cash provided by investing"
       }
      }
     },
     "localname": "CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations": {
     "auth_ref": [
      "r12",
      "r96"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash inflow (outflow) of operating activities of discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.",
        "label": "Cash Provided By Used In Operating Activities Discontinued Operations",
        "terseLabel": "Net cash flows used in operations"
       }
      }
     },
     "localname": "CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYieldMovementScheduleRollForward": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.",
        "label": "Certain Loans Acquired In Transfer Accounted For As Debt Securities Accretable Yield Movement Schedule Roll Forward",
        "terseLabel": "Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]"
       }
      }
     },
     "localname": "CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYieldMovementScheduleRollForward",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfChangesToAccretableYieldForPCILoansDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield": {
     "auth_ref": [
      "r176",
      "r177"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.",
        "label": "Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield",
        "periodEndLabel": "Balance, end of period",
        "periodStartLabel": "Balance, beginning of period"
       }
      }
     },
     "localname": "CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfChangesToAccretableYieldForPCILoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAccretion": {
     "auth_ref": [
      "r176",
      "r177"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of accretion recognized for the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities, with evidence of deterioration of credit quality.",
        "label": "Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Accretion",
        "negatedLabel": "Accretion into interest income"
       }
      }
     },
     "localname": "CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAccretion",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfChangesToAccretableYieldForPCILoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldDisposalsOfLoans": {
     "auth_ref": [
      "r176",
      "r177"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of reduction, resulting from a sale or transfer of a loan, in the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.",
        "label": "Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Disposals Of Loans",
        "negatedLabel": "Disposals and Other"
       }
      }
     },
     "localname": "CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldDisposalsOfLoans",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfChangesToAccretableYieldForPCILoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldReclassificationsFromNonaccretableDifference": {
     "auth_ref": [
      "r176",
      "r177"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase of reclassification from nonaccretable difference to the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.",
        "label": "Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Accretable Yield Reclassifications From Nonaccretable Difference",
        "terseLabel": "Reclassification from non-accretable difference"
       }
      }
     },
     "localname": "CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldReclassificationsFromNonaccretableDifference",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfChangesToAccretableYieldForPCILoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAllowanceForLoanLosses": {
     "auth_ref": [
      "r176",
      "r178"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Reserve for loans impairments recorded after acquisition as a result of current information and events which result in it being probable that estimated cash flows will be less than previously expected or because actual cash flows are less than cash flows previously expected.  This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.",
        "label": "Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Allowance For Loan Losses",
        "terseLabel": "Loans acquired with deteriorated credit quality"
       }
      }
     },
     "localname": "CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAllowanceForLoanLosses",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ChangeDuringPeriodFairValueDisclosureMember": {
     "auth_ref": [
      "r412"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measure of change in fair value.",
        "label": "Change During Period Fair Value Disclosure [Member]",
        "terseLabel": "Total Gains (Losses)"
       }
      }
     },
     "localname": "ChangeDuringPeriodFairValueDisclosureMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ClassOfStockDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Share of stock differentiated by the voting rights the holder receives. Examples include, but are not limited to, common stock, redeemable preferred stock, nonredeemable preferred stock, and convertible stock.",
        "label": "Class Of Stock [Domain]",
        "terseLabel": "Class of Stock"
       }
      }
     },
     "localname": "ClassOfStockDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ClassOfTreasuryStockTable": {
     "auth_ref": [
      "r306",
      "r307",
      "r308",
      "r309"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about treasury stock, including, but not limited to, average cost per share, description of share repurchase program, shares repurchased, shares held for each class of treasury stock.",
        "label": "Class Of Treasury Stock [Table]",
        "terseLabel": "Class Of Treasury Stock [Table]"
       }
      }
     },
     "localname": "ClassOfTreasuryStockTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ClassificationOfVariableInterestEntityDomain": {
     "auth_ref": [
      "r350",
      "r353",
      "r354",
      "r356"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Categorization of Variable Interest Entities (VIE) for consolidation and (or) disclosure purposes, whether individually or in aggregate, by: (1) VIEs consolidated because the entity is the primary beneficiary, (2) VIEs not consolidated because the entity is not the primary beneficiary, and (3) VIEs or potential VIEs that are not consolidated because necessary information is not available. In general, a VIE is a corporation, partnership, trust, or any other legal structure used for business purposes that either (a) does not have equity investors with voting rights or (b) has equity investors that do not provide sufficient financial resources for the entity to support its activities. A VIE often holds financial assets, including loans or receivables, real estate or other property. A VIE may be essentially passive or it may engage in research and development or other activities on behalf of another company.",
        "label": "Classification Of Variable Interest Entity [Domain]",
        "terseLabel": "Variable Interest Entity, Classification"
       }
      }
     },
     "localname": "ClassificationOfVariableInterestEntityDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommercialLoanMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A loan, whether secured or unsecured, to a company for purposes such as seasonal working capital needs, inventory financing, equipment purchases and acquisitions.",
        "label": "Commercial Loan [Member]",
        "terseLabel": "Commercial Loan"
       }
      }
     },
     "localname": "CommercialLoanMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfModificationsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommercialPortfolioSegmentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Portfolio segment of the company's total financing receivables related to commercial receivables.",
        "label": "Commercial Portfolio Segment [Member]",
        "terseLabel": "Commercial Loans"
       }
      }
     },
     "localname": "CommercialPortfolioSegmentMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfTdrsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommitmentsAndContingenciesDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Commitments And Contingencies Disclosure [Abstract]"
       }
      }
     },
     "localname": "CommitmentsAndContingenciesDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_CommitmentsAndContingenciesPolicyTextBlock": {
     "auth_ref": [
      "r109",
      "r293",
      "r538",
      "r539"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy for commitments and contingencies, which may include policies for recognizing and measuring loss and gain contingencies.",
        "label": "Commitments And Contingencies Policy [Text Block]",
        "terseLabel": "Litigation and other Contingencies"
       }
      }
     },
     "localname": "CommitmentsAndContingenciesPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CommitmentsDisclosureTextBlock": {
     "auth_ref": [
      "r277"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for significant arrangements with third parties, which includes operating lease arrangements and arrangements in which the entity has agreed to expend funds to procure goods or services, or has agreed to commit resources to supply goods or services, and operating lease arrangements. Descriptions may include identification of the specific goods and services, period of time covered, minimum quantities and amounts, and cancellation rights.",
        "label": "Commitments Disclosure [Text Block]",
        "terseLabel": "COMMITMENTS"
       }
      }
     },
     "localname": "CommitmentsDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitments"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CommitmentsMember": {
     "auth_ref": [
      "r21",
      "r276",
      "r453",
      "r512"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This element represents significant arrangements with third parties, which includes operating lease arrangements and arrangements in which the entity has agreed to expend funds to procure goods or services, or has agreed to commit resources to supply goods or services, and operating lease arrangements.",
        "label": "Commitments [Member]",
        "verboseLabel": "Commitments to tax credit investments"
       }
      }
     },
     "localname": "CommitmentsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommonEquityTierOneCapital": {
     "auth_ref": [
      "r499"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of Common Equity Tier One Risk-based Capital, as defined by regulatory framework.",
        "label": "Common Equity Tier One Capital",
        "terseLabel": "Common Equity Tier 1 Capital"
       }
      }
     },
     "localname": "CommonEquityTierOneCapital",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CommonEquityTierOneCapitalAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Common Equity Tier One Capital [Abstract]",
        "terseLabel": "Common Equity Tier 1 Capital Ratio:"
       }
      }
     },
     "localname": "CommonEquityTierOneCapitalAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CommonStockDividendsPerShareCashPaid": {
     "auth_ref": [
      "r305"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate dividends paid during the period for each share of common stock outstanding.",
        "label": "Common Stock Dividends Per Share Cash Paid",
        "terseLabel": "Dividends paid per common share"
       }
      }
     },
     "localname": "CommonStockDividendsPerShareCashPaid",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_CommonStockMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Stock that is subordinate to all other stock of the issuer.",
        "label": "Common Stock [Member]",
        "terseLabel": "Common Stock",
        "verboseLabel": "Issued"
       }
      }
     },
     "localname": "CommonStockMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommonStockParOrStatedValuePerShare": {
     "auth_ref": [
      "r24"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Face amount or stated value per share of common stock.",
        "label": "Common Stock Par Or Stated Value Per Share",
        "terseLabel": "Common Stock, par value (in dollars per share)"
       }
      }
     },
     "localname": "CommonStockParOrStatedValuePerShare",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_CommonStockSharesAuthorized": {
     "auth_ref": [
      "r24"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The maximum number of common shares permitted to be issued by an entity's charter and bylaws.",
        "label": "Common Stock Shares Authorized",
        "terseLabel": "Common Stock, shares authorized (in shares)"
       }
      }
     },
     "localname": "CommonStockSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockSharesIssued": {
     "auth_ref": [
      "r24"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.",
        "label": "Common Stock Shares Issued",
        "periodEndLabel": "Ending balance, issued (in shares)",
        "periodStartLabel": "Beginning balance, issued (in shares)",
        "terseLabel": "Common Stock, shares issued (in shares)"
       }
      }
     },
     "localname": "CommonStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockSharesOutstanding": {
     "auth_ref": [
      "r24",
      "r300"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.",
        "label": "Common Stock Shares Outstanding",
        "periodEndLabel": "Ending balance, outstanding (in shares)",
        "periodStartLabel": "Beginning balance, outstanding (in shares)",
        "terseLabel": "Common Stock, shares outstanding (in shares)"
       }
      }
     },
     "localname": "CommonStockSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockValue": {
     "auth_ref": [
      "r24"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10050.0,
       "parentTag": "cit_CommonStockholdersEquityAttributableToParent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate par or stated value of issued nonredeemable common stock (or common stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable common shares, par value and other disclosure concepts are in another section within stockholders' equity.",
        "label": "Common Stock Value",
        "terseLabel": "Common Stock: $0.01 par value, 600,000,000 shares authorized Issued: 0 at March 31, 2020 and 162,188,287 at December 31, 2019 Outstanding: 0 at March 31, 2020 and 94,742,564 at December 31, 2019"
       }
      }
     },
     "localname": "CommonStockValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]",
        "terseLabel": "Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]"
       }
      }
     },
     "localname": "ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ComprehensiveIncomeNetOfTax": {
     "auth_ref": [
      "r68",
      "r70",
      "r71"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.",
        "label": "Comprehensive Income Net Of Tax",
        "totalLabel": "Comprehensive (loss) income"
       }
      }
     },
     "localname": "ComprehensiveIncomeNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ConsolidationPolicyTextBlock": {
     "auth_ref": [
      "r109",
      "r347",
      "r359",
      "r360"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy regarding (1) the principles it follows in consolidating or combining the separate financial statements, including the principles followed in determining the inclusion or exclusion of subsidiaries or other entities in the consolidated or combined financial statements and (2) its treatment of interests (for example, common stock, a partnership interest or other means of exerting influence) in other entities, for example consolidation or use of the equity or cost methods of accounting.  The accounting policy may also address the accounting treatment for intercompany accounts and transactions, noncontrolling interest, and the income statement treatment in consolidation for issuances of stock by a subsidiary.",
        "label": "Consolidation Policy [Text Block]",
        "terseLabel": "Principles of Consolidation"
       }
      }
     },
     "localname": "ConsolidationPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ConsumerLoanMember": {
     "auth_ref": [
      "r239"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loan or extension of credit for personal, family, or household use excluding real estate.",
        "label": "Consumer Loan [Member]",
        "terseLabel": "Consumer Loan"
       }
      }
     },
     "localname": "ConsumerLoanMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ConsumerPortfolioSegmentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Portfolio segment of the company's total financing receivables related to consumer receivables.",
        "label": "Consumer Portfolio Segment [Member]",
        "terseLabel": "Consumer Loans"
       }
      }
     },
     "localname": "ConsumerPortfolioSegmentMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfTdrsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ContractualMaturitiesTimeDeposits100000OrMoreAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Contractual Maturities Time Deposits100000 Or More [Abstract]",
        "terseLabel": "Time Deposits:"
       }
      }
     },
     "localname": "ContractualMaturitiesTimeDeposits100000OrMoreAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ContractualMaturitiesTimeDeposits100000OrMoreAfter12Months": {
     "auth_ref": [
      "r545"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails": {
       "order": 10040.0,
       "parentTag": "us-gaap_TimeDeposits100000OrMore",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposit liabilities, including certificates of deposit, in denominations of $100,000 or more, maturing after twelve months from the balance sheet date.",
        "label": "Contractual Maturities Time Deposits100000 Or More After12 Months",
        "terseLabel": "After twelve months"
       }
      }
     },
     "localname": "ContractualMaturitiesTimeDeposits100000OrMoreAfter12Months",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ContractualMaturitiesTimeDeposits100000OrMoreSixMonthsThrough12Months": {
     "auth_ref": [
      "r545"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_TimeDeposits100000OrMore",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposit liabilities, including certificates of deposit, in denominations of $100,000 or more, maturing within six to twelve months after the balance sheet date.",
        "label": "Contractual Maturities Time Deposits100000 Or More Six Months Through12 Months",
        "terseLabel": "After six months through twelve months"
       }
      }
     },
     "localname": "ContractualMaturitiesTimeDeposits100000OrMoreSixMonthsThrough12Months",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ContractualMaturitiesTimeDeposits100000OrMoreThreeMonthsOrLess": {
     "auth_ref": [
      "r545"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_TimeDeposits100000OrMore",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposit liabilities, including certificates of deposit, in denominations of $100,000 or more, maturing within three months or fewer from the balance sheet date.",
        "label": "Contractual Maturities Time Deposits100000 Or More Three Months Or Less",
        "terseLabel": "Three months or less"
       }
      }
     },
     "localname": "ContractualMaturitiesTimeDeposits100000OrMoreThreeMonthsOrLess",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ContractualMaturitiesTimeDeposits100000OrMoreThreeMonthsThroughSixMonths": {
     "auth_ref": [
      "r545"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_TimeDeposits100000OrMore",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposit liabilities, including certificates of deposit, in denominations of $100,000 or more, maturing within three to six months after the balance sheet date.",
        "label": "Contractual Maturities Time Deposits100000 Or More Three Months Through Six Months",
        "terseLabel": "After three months through six months"
       }
      }
     },
     "localname": "ContractualMaturitiesTimeDeposits100000OrMoreThreeMonthsThroughSixMonths",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CoreDepositsMember": {
     "auth_ref": [
      "r494"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Entity's long-term relationships with depositors, commonly known as core deposit intangibles, which are separate from the financial instruments themselves.",
        "label": "Core Deposits [Member]",
        "terseLabel": "Core Deposit Intangibles",
        "verboseLabel": "Core deposit intangibles"
       }
      }
     },
     "localname": "CoreDepositsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CorporateNonSegmentMember": {
     "auth_ref": [
      "r141"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Corporate headquarters or functional department that may not earn revenues or may earn revenues that are only incidental to the activities of the entity and is not considered an operating segment.",
        "label": "Corporate Non Segment [Member]",
        "terseLabel": "Corporate"
       }
      }
     },
     "localname": "CorporateNonSegmentMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CostOfOtherPropertyOperatingExpense": {
     "auth_ref": [
      "r80"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails": {
       "order": 10070.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": -1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10140.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other operating costs incurred during the reporting period and may include amounts paid to maintain the property.",
        "label": "Cost Of Other Property Operating Expense",
        "terseLabel": "Maintenance and other operating lease expenses"
       }
      }
     },
     "localname": "CostOfOtherPropertyOperatingExpense",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CreditFacilityAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of credit facility. Credit facilities provide capital to borrowers without the need to structure a loan for each borrowing.",
        "label": "Credit Facility [Axis]",
        "terseLabel": "Credit Facility"
       }
      }
     },
     "localname": "CreditFacilityAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CreditFacilityDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Type of credit facility. Credit facilities provide capital to borrowers without the need to structure a loan for each borrowing.",
        "label": "Credit Facility [Domain]",
        "terseLabel": "Credit Facility"
       }
      }
     },
     "localname": "CreditFacilityDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CreditLossAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Credit Loss [Abstract]"
       }
      }
     },
     "localname": "CreditLossAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_CreditLossStatusAxis": {
     "auth_ref": [
      "r179",
      "r241",
      "r248"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by credit loss status of financial asset.",
        "label": "Credit Loss Status [Axis]",
        "terseLabel": "Credit Loss Status"
       }
      }
     },
     "localname": "CreditLossStatusAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansInProcessOfForeclosureParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CreditLossStatusDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Credit loss status of financial asset.",
        "label": "Credit Loss Status [Domain]",
        "terseLabel": "Credit Loss Status"
       }
      }
     },
     "localname": "CreditLossStatusDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansInProcessOfForeclosureParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CreditScoreFicoAxis": {
     "auth_ref": [
      "r228",
      "r236"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by credit scores as defined by Fair Isaac Corporation (FICO), for example, but not limited to, greater than 740.",
        "label": "Credit Score Fico [Axis]",
        "terseLabel": "Credit Score, FICO"
       }
      }
     },
     "localname": "CreditScoreFicoAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CreditScoreFicoDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Credit rating as defined by Fair Isaac Corporation (FICO), for example, but not limited to, greater than 740. Element name and standard label in FICO Score [numeric lower end] to [numeric higher end] [Member] format for ranges. Element name and standard label in FICO Score Greater Than [low end numeric value] [Member] or FICO Score Less Than [high end numeric value] [Member] formats for greater than or less than disclosures.",
        "label": "Credit Score Fico [Domain]",
        "terseLabel": "Credit Score, FICO"
       }
      }
     },
     "localname": "CreditScoreFicoDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CriticizedMember": {
     "auth_ref": [
      "r228"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Credit rating classification which identifies weaknesses related to credit risk. Includes, but is not limited to, special mention, substandard and doubtful classifications. Excludes noncriticized classification.",
        "label": "Criticized [Member]",
        "verboseLabel": "Criticized Loans"
       }
      }
     },
     "localname": "CriticizedMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.",
        "label": "Cumulative Effect Of New Accounting Principle In Period Of Adoption",
        "periodEndLabel": "Adoption of Accounting Standard Update",
        "periodStartLabel": "Adoption of Accounting Standard Update",
        "terseLabel": "Adoption of ASUs 2016-01 and 2018-02"
       }
      }
     },
     "localname": "CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CustomerRelationshipsMember": {
     "auth_ref": [
      "r336"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Customer relationship that exists between an entity and its customer, for example, but not limited to, tenant relationships.",
        "label": "Customer Relationships [Member]",
        "terseLabel": "Customer Relationships",
        "verboseLabel": "Customer relationships"
       }
      }
     },
     "localname": "CustomerRelationshipsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DebtDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Debt Disclosure [Abstract]"
       }
      }
     },
     "localname": "DebtDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtInstrumentBasisSpreadOnVariableRate1": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage points added to the reference rate to compute the variable rate on the debt instrument.",
        "label": "Debt Instrument Basis Spread On Variable Rate1",
        "terseLabel": "Debt, applicable margin (percentage)"
       }
      }
     },
     "localname": "DebtInstrumentBasisSpreadOnVariableRate1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_DebtInstrumentFaceAmount": {
     "auth_ref": [
      "r417",
      "r419"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Face (par) amount of debt instrument at time of issuance.",
        "label": "Debt Instrument Face Amount",
        "verboseLabel": "Face amount"
       }
      }
     },
     "localname": "DebtInstrumentFaceAmount",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtInstrumentFairValue": {
     "auth_ref": [
      "r409"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.",
        "label": "Debt Instrument Fair Value",
        "negatedLabel": "Borrowings"
       }
      }
     },
     "localname": "DebtInstrumentFairValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtInstrumentLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Debt Instrument [Line Items]",
        "terseLabel": "Debt Instrument [Line Items]"
       }
      }
     },
     "localname": "DebtInstrumentLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtInstrumentTable": {
     "auth_ref": [
      "r36",
      "r112",
      "r301",
      "r302",
      "r303",
      "r304",
      "r416",
      "r417",
      "r419",
      "r498"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A table or schedule providing information pertaining to long-term debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the company, if longer.",
        "label": "Debt Instrument [Table]",
        "terseLabel": "Debt Instrument [Table]"
       }
      }
     },
     "localname": "DebtInstrumentTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger": {
     "auth_ref": [
      "r196",
      "r244",
      "r247"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.",
        "label": "Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer",
        "terseLabel": "Total securities available-for-sale, 12 months or greater, Debt securities, Fair Value"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss": {
     "auth_ref": [
      "r196",
      "r244"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.",
        "label": "Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss",
        "negatedLabel": "Total securities available-for-sale, 12 months or greater, Debt securities, Gross Unrealized Loss"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months": {
     "auth_ref": [
      "r196",
      "r244",
      "r247"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.",
        "label": "Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months",
        "terseLabel": "Total securities available-for-sale, Less than 12 months, Debt securities, Fair Value"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss": {
     "auth_ref": [
      "r196",
      "r244"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.",
        "label": "Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss",
        "negatedLabel": "Total securities available-for-sale, Less than 12 months, Debt securities, Gross Unrealized Loss"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput": {
     "auth_ref": [
      "r396"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value of input used to measure investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Debt Securities Available For Sale Measurement Input",
        "terseLabel": "Securities \u2014 AFS measurement input"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleMeasurementInput",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "decimalItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLossExcludingOtherThanTemporaryImpairment": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), excluding other-than-temporary impairment (OTTI).",
        "label": "Debt Securities Available For Sale Realized Gain Loss Excluding Other Than Temporary Impairment",
        "terseLabel": "Realized gains on available-for-sale securities excluding losses from other than temporary impairment (\"OTTI\")"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleRealizedGainLossExcludingOtherThanTemporaryImpairment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleTable": {
     "auth_ref": [
      "r198"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Debt Securities Available For Sale [Table]",
        "terseLabel": "Debt Securities Available For Sale [Table]"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleTableTextBlock": {
     "auth_ref": [
      "r198"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Debt Securities Available For Sale Table [Text Block]",
        "terseLabel": "Amortized Cost and Fair Value of Securities Available-For-Sale"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DebtSecuritiesMember": {
     "auth_ref": [
      "r198"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt instrument issued by corporations, governments and governmental agencies, municipalities, and other institutions.",
        "label": "Debt Securities [Member]",
        "verboseLabel": "Debt Securities"
       }
      }
     },
     "localname": "DebtSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DeferredIncomeTaxExpenseBenefit": {
     "auth_ref": [
      "r100",
      "r110",
      "r320",
      "r321"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10260.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.",
        "label": "Deferred Income Tax Expense Benefit",
        "terseLabel": "Provision for deferred income taxes"
       }
      }
     },
     "localname": "DeferredIncomeTaxExpenseBenefit",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DepositLiabilitiesDisclosuresTextBlock": {
     "auth_ref": [
      "r461",
      "r492"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for deposit liabilities including data and tables. It may include a description of the entity's deposit liabilities, the aggregate amount of time deposits (including certificates of deposit) in denominations of $100,000 or more at the balance sheet date; the aggregate amount of any demand deposits that have been reclassified as loan balances, such as overdrafts, at the balance sheet date; deposits that are received on terms other than those in the normal course of business, the amount of accrued interest on deposit liabilities; securities, mortgage loans or other financial instruments that serve as collateral for deposits; for time deposits having a remaining term of more than one year, the aggregate amount of maturities for each of the five years following the balance sheet date; and the weighted average interest rate for all deposit liabilities held by the entity.",
        "label": "Deposit Liabilities Disclosures [Text Block]",
        "terseLabel": "DEPOSITS"
       }
      }
     },
     "localname": "DepositLiabilitiesDisclosuresTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDeposits"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DepositLiabilitiesTypeTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of type of deposit liability.",
        "label": "Deposit Liabilities Type Table [Text Block]",
        "terseLabel": "Schedule of Detail on Deposit Types"
       }
      }
     },
     "localname": "DepositLiabilitiesTypeTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_Deposits": {
     "auth_ref": [
      "r461"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfDetailOnDepositTypesDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10100.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.",
        "label": "Deposits",
        "terseLabel": "Deposits",
        "totalLabel": "Total deposits"
       }
      }
     },
     "localname": "Deposits",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfDetailOnDepositTypesDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DepositsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Deposits [Abstract]"
       }
      }
     },
     "localname": "DepositsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_Depreciation": {
     "auth_ref": [
      "r100",
      "r271"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10220.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.",
        "label": "Depreciation",
        "terseLabel": "Depreciation on operating lease equipment"
       }
      }
     },
     "localname": "Depreciation",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeAssetFairValueGrossLiability": {
     "auth_ref": [
      "r44",
      "r51",
      "r371"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.",
        "label": "Derivative Asset Fair Value Gross Liability",
        "negatedLabel": "Less: Gross amounts offset in the Consolidated Balance Sheets, Asset Fair Value"
       }
      }
     },
     "localname": "DerivativeAssetFairValueGrossLiability",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeAssetFairValueOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection": {
     "auth_ref": [
      "r47",
      "r49"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value, after effects of master netting arrangements, deduction of assets not subject to a master netting arrangement and elected not to be offset, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, offset against an obligation to return collateral.",
        "label": "Derivative Asset Fair Value Offset Against Collateral Net Of Not Subject To Master Netting Arrangement Policy Election",
        "terseLabel": "Total net derivative fair values, Asset Fair Value"
       }
      }
     },
     "localname": "DerivativeAssetFairValueOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeAssetMeasurementInput": {
     "auth_ref": [
      "r396"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value of input used to measure derivative asset.",
        "label": "Derivative Asset Measurement Input",
        "terseLabel": "Derivative assets \u2014 non qualifying, measurement input"
       }
      }
     },
     "localname": "DerivativeAssetMeasurementInput",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "decimalItemType"
    },
    "us-gaap_DerivativeAssets": {
     "auth_ref": [
      "r45",
      "r48",
      "r409"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.",
        "label": "Derivative Assets",
        "terseLabel": "Net amount presented in the Consolidated Balance Sheets, Derivative assets"
       }
      }
     },
     "localname": "DerivativeAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeCollateralObligationToReturnCash": {
     "auth_ref": [
      "r46",
      "r49",
      "r387"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.",
        "label": "Derivative Collateral Obligation To Return Cash",
        "negatedLabel": "Cash collateral pledged (received) subject to master netting agreements, Asset Fair Value"
       }
      }
     },
     "localname": "DerivativeCollateralObligationToReturnCash",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeCollateralRightToReclaimCash": {
     "auth_ref": [
      "r46",
      "r49",
      "r387"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.",
        "label": "Derivative Collateral Right To Reclaim Cash",
        "terseLabel": "Cash collateral pledged (received) subject to master netting agreements Liability Fair Value"
       }
      }
     },
     "localname": "DerivativeCollateralRightToReclaimCash",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeContractTypeDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financial instrument or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.",
        "label": "Derivative Contract Type [Domain]",
        "terseLabel": "Derivative Contract"
       }
      }
     },
     "localname": "DerivativeContractTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DerivativeFairValueOfDerivativeAsset": {
     "auth_ref": [
      "r43",
      "r50",
      "r371",
      "r442"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.",
        "label": "Derivative Fair Value Of Derivative Asset",
        "terseLabel": "Asset Fair Value"
       }
      }
     },
     "localname": "DerivativeFairValueOfDerivativeAsset",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeFairValueOfDerivativeLiability": {
     "auth_ref": [
      "r43",
      "r50",
      "r371",
      "r442"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.",
        "label": "Derivative Fair Value Of Derivative Liability",
        "negatedLabel": "Liability Fair Value"
       }
      }
     },
     "localname": "DerivativeFairValueOfDerivativeLiability",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeFinancialInstrumentsAssetsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This element represents types of derivative financial instruments which are financial instruments or other contractual arrangements with all three of the following characteristics: (a) it has (1) one or more underlyings and (2) one or more notional amounts or payment provisions or both. Those terms determine the amount of the settlement or settlements, and, in some cases, whether or not a settlement is required; (b) it requires no initial net investment or an initial net investment that is smaller than would be required for other types of contracts that would be expected to have a similar response to changes in market factors; and (c) its terms require or permit net settlement, it can readily be settled net by a means outside the contract, or it provides for delivery of an asset that puts the recipient in a position not substantially different from net settlement. Notwithstanding the above characteristics, loan commitments that relate to the origination of mortgage loans that will be held for sale are accounted for as derivative instruments by the issuer of the loan commitment (that is, the potential lender).",
        "label": "Derivative Financial Instruments Assets [Member]",
        "terseLabel": "Derivative Assets \u2014 Non-Qualifying"
       }
      }
     },
     "localname": "DerivativeFinancialInstrumentsAssetsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This item represents derivative instrument obligations meeting the definition of a liability which are reported as of the balance sheet date. Derivative instrument obligations are generally measured at fair value, and adjustments to the carrying amount of hedged items reflect changes in their fair value (that is, losses) that are attributable to the risk being hedged and that arise while the hedge is in effect.",
        "label": "Derivative Financial Instruments Liabilities [Member]",
        "terseLabel": "Derivative Liabilities \u2014 Non-Qualifying",
        "verboseLabel": "Derivative Liabilities \u2014 Non-Qualifying"
       }
      }
     },
     "localname": "DerivativeFinancialInstrumentsLiabilitiesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DerivativeGainLossOnDerivativeNet": {
     "auth_ref": [
      "r370"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.",
        "label": "Derivative Gain Loss On Derivative Net",
        "terseLabel": "Non-qualifying hedges - income statement impact"
       }
      }
     },
     "localname": "DerivativeGainLossOnDerivativeNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeInstrumentRiskAxis": {
     "auth_ref": [
      "r369",
      "r372",
      "r376",
      "r382"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of derivative contract.",
        "label": "Derivative Instrument Risk [Axis]",
        "terseLabel": "Derivative Instrument"
       }
      }
     },
     "localname": "DerivativeInstrumentRiskAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Derivative Instruments And Hedging Activities Disclosure [Abstract]"
       }
      }
     },
     "localname": "DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock": {
     "auth_ref": [
      "r390"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.",
        "label": "Derivative Instruments And Hedging Activities Disclosure [Text Block]",
        "terseLabel": "Derivative Financial Instruments"
       }
      }
     },
     "localname": "DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstruments"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis": {
     "auth_ref": [
      "r367",
      "r369",
      "r376"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of hedging relationship.",
        "label": "Derivative Instruments Gain Loss By Hedging Relationship [Axis]",
        "terseLabel": "Hedging Relationship"
       }
      }
     },
     "localname": "DerivativeInstrumentsGainLossByHedgingRelationshipAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable": {
     "auth_ref": [
      "r367",
      "r369",
      "r376",
      "r382",
      "r383",
      "r388",
      "r389"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about the location and amount of derivative instruments and nonderivative instruments designated as hedging instruments reported before netting adjustments, and the amount of gain (loss) on derivative instruments and nonderivative instruments designated and qualified as hedging instruments.",
        "label": "Derivative Instruments Gain Loss By Hedging Relationship By Income Statement Location By Derivative Instrument Risk [Table]",
        "terseLabel": "Derivative Instruments Gain Loss By Hedging Relationship By Income Statement Location By Derivative Instrument Risk [Table]"
       }
      }
     },
     "localname": "DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeInstrumentsGainLossLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Derivative Instruments Gain Loss [Line Items]",
        "terseLabel": "Derivative Instruments, Gain (Loss) [Line Items]",
        "verboseLabel": "Derivative Instruments, Gain (Loss) [Line Items]"
       }
      }
     },
     "localname": "DerivativeInstrumentsGainLossLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet": {
     "auth_ref": [
      "r375",
      "r381"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.",
        "label": "Derivative Instruments Gain Loss Reclassified From Accumulated O C I Into Income Effective Portion Net",
        "terseLabel": "Amounts reclassified from AOCI to income"
       }
      }
     },
     "localname": "DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeInstrumentsInHedgesAtFairValueNet": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate net fair value of all derivative instruments designated as hedging instruments. Includes instruments designated as cash flow hedges, fair value hedges, and hedges of net investments in foreign operations.",
        "label": "Derivative Instruments In Hedges At Fair Value Net",
        "terseLabel": "Fair value on derivative instruments"
       }
      }
     },
     "localname": "DerivativeInstrumentsInHedgesAtFairValueNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeLiabilities": {
     "auth_ref": [
      "r45",
      "r48",
      "r409"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.",
        "label": "Derivative Liabilities",
        "negatedLabel": "Net amount presented in the Consolidated Balance Sheets, Derivative liabilities"
       }
      }
     },
     "localname": "DerivativeLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeLiabilityFairValueGrossAsset": {
     "auth_ref": [
      "r44",
      "r51",
      "r371"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of asset associated with financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.",
        "label": "Derivative Liability Fair Value Gross Asset",
        "terseLabel": "Less: Gross amounts offset in the Consolidated Balance Sheets, Liability Fair Value"
       }
      }
     },
     "localname": "DerivativeLiabilityFairValueGrossAsset",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeLiabilityFairValueOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection": {
     "auth_ref": [
      "r47",
      "r49"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value, after effects of master netting arrangements, deduction of liabilities not subject to a master netting arrangement and elected not to be offset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, offset against the right to receive collateral.",
        "label": "Derivative Liability Fair Value Offset Against Collateral Net Of Not Subject To Master Netting Arrangement Policy Election",
        "negatedLabel": "Total net derivative fair values, Liability Fair Value"
       }
      }
     },
     "localname": "DerivativeLiabilityFairValueOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeMember": {
     "auth_ref": [
      "r362"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This element represents types of derivative financial instruments which are financial instruments or other contractual arrangements with all three of the following characteristics: (a) it has (1) one or more underlyings and (2) one or more notional amounts or payment provisions or both. Those terms determine the amount of the settlement or settlements, and, in some cases, whether or not a settlement is required; (b) it requires no initial net investment or an initial net investment that is smaller than would be required for other types of contracts that would be expected to have a similar response to changes in market factors; and (c) its terms require or permit net settlement, it can readily be settled net by a means outside the contract, or it provides for delivery of an asset that puts the recipient in a position not substantially different from net settlement. Notwithstanding the above characteristics, loan commitments that relate to the origination of mortgage loans that will be held for sale are accounted for as derivative instruments by the issuer of the loan commitment (that is, the potential lender).",
        "label": "Derivative [Member]",
        "terseLabel": "Recognized on Derivatives"
       }
      }
     },
     "localname": "DerivativeMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DerivativeNotionalAmount": {
     "auth_ref": [
      "r363",
      "r364"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Nominal or face amount used to calculate payment on derivative.",
        "label": "Derivative Notional Amount",
        "terseLabel": "Notional Amount"
       }
      }
     },
     "localname": "DerivativeNotionalAmount",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DesignatedAsHedgingInstrumentMember": {
     "auth_ref": [
      "r367"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative instrument designated as hedging instrument under Generally Accepted Accounting Principles (GAAP).",
        "label": "Designated As Hedging Instrument [Member]",
        "terseLabel": "Derivatives designated as hedging instruments (Qualifying Hedges)",
        "verboseLabel": "Qualifying Hedges"
       }
      }
     },
     "localname": "DesignatedAsHedgingInstrumentMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10040.0,
       "parentTag": "us-gaap_EarningsPerShareBasic",
       "weight": 1.0
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Per basic share amount, after tax, of income (loss) from the day-to-day business activities of the discontinued operation.",
        "label": "Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share",
        "terseLabel": "Loss from discontinued operations"
       }
      }
     },
     "localname": "DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerDilutedShare": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10020.0,
       "parentTag": "us-gaap_EarningsPerShareDiluted",
       "weight": 1.0
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Per diluted share amount, after tax, of income (loss) from the day-to-day business activities of the discontinued operation.",
        "label": "Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Diluted Share",
        "terseLabel": "Income (loss) from discontinued operations"
       }
      }
     },
     "localname": "DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerDilutedShare",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_DiscontinuedOperationsPolicyTextBlock": {
     "auth_ref": [
      "r10",
      "r15",
      "r109",
      "r129"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy for discontinued operations. Includes, but is not limited to, method of interest allocation to a discontinued operation.",
        "label": "Discontinued Operations Policy [Text Block]",
        "terseLabel": "Discontinued Operations"
       }
      }
     },
     "localname": "DiscontinuedOperationsPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DisposalGroupClassificationAxis": {
     "auth_ref": [
      "r13"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by disposal group classification.",
        "label": "Disposal Group Classification [Axis]",
        "terseLabel": "Disposal Group Classification"
       }
      }
     },
     "localname": "DisposalGroupClassificationAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DisposalGroupClassificationDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Component or group of components disposed of, including but not limited to, disposal group held-for-sale or disposed of by sale, disposed of by means other than sale, and discontinued operations.",
        "label": "Disposal Group Classification [Domain]",
        "terseLabel": "Disposal Group Classification"
       }
      }
     },
     "localname": "DisposalGroupClassificationDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DividendIncomeEquitySecuritiesOperating": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfInterestAndDividendIncomeDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_InterestAndDividendIncomeSecurities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of dividend income on investment in equity security, classified as operating.",
        "label": "Dividend Income Equity Securities Operating",
        "terseLabel": "Dividends - equity securities"
       }
      }
     },
     "localname": "DividendIncomeEquitySecuritiesOperating",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfInterestAndDividendIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Dividends": {
     "auth_ref": [
      "r305",
      "r491"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of paid and unpaid cash, stock, and paid-in-kind (PIK) dividends declared, for example, but not limited to, common and preferred stock.",
        "label": "Dividends",
        "negatedLabel": "Dividends paid"
       }
      }
     },
     "localname": "Dividends",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EarningsPerShareBasic": {
     "auth_ref": [
      "r78",
      "r119",
      "r124",
      "r126",
      "r127",
      "r128",
      "r130",
      "r474",
      "r523"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.",
        "label": "Earnings Per Share Basic",
        "totalLabel": "Basic (loss) income per share"
       }
      }
     },
     "localname": "EarningsPerShareBasic",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_EarningsPerShareBasicAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Earnings Per Share Basic [Abstract]",
        "terseLabel": "Basic (loss) income per common share"
       }
      }
     },
     "localname": "EarningsPerShareBasicAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Earnings Per Share Basic And Diluted Other Disclosures [Abstract]",
        "terseLabel": "Average number of common shares (thousands)"
       }
      }
     },
     "localname": "EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EarningsPerShareDiluted": {
     "auth_ref": [
      "r78",
      "r119",
      "r124",
      "r126",
      "r127",
      "r128",
      "r130",
      "r474",
      "r523"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.",
        "label": "Earnings Per Share Diluted",
        "totalLabel": "Diluted (loss) income per share"
       }
      }
     },
     "localname": "EarningsPerShareDiluted",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_EarningsPerShareDilutedAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Earnings Per Share Diluted [Abstract]",
        "terseLabel": "Diluted (loss) income per common share"
       }
      }
     },
     "localname": "EarningsPerShareDilutedAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations": {
     "auth_ref": [
      "r413"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10040.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase (decrease) from effect of exchange rate changes on cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; held in foreign currencies; including, but not limited to, disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.",
        "label": "Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations",
        "terseLabel": "Effect of exchange rate changes on cash and cash equivalents"
       }
      }
     },
     "localname": "EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperationsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations [Abstract]",
        "terseLabel": "Reconciliation of cash, cash equivalents and restricted cash"
       }
      }
     },
     "localname": "EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperationsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnauditedParenthetical"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EffectiveIncomeTaxRateContinuingOperations": {
     "auth_ref": [
      "r113",
      "r318",
      "r319"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.",
        "label": "Effective Income Tax Rate Continuing Operations",
        "terseLabel": "Effective income tax rate percentage"
       }
      }
     },
     "localname": "EffectiveIncomeTaxRateContinuingOperations",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureIncomeTaxesNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_EquityClassOfTreasuryStockLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Equity Class Of Treasury Stock [Line Items]",
        "terseLabel": "Equity Class Of Treasury Stock [Line Items]"
       }
      }
     },
     "localname": "EquityClassOfTreasuryStockLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EquityComponentDomain": {
     "auth_ref": [
      "r300"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Components of equity are the parts of the total Equity balance including that which is allocated to common, preferred, treasury stock, retained earnings, etc.",
        "label": "Equity Component [Domain]",
        "terseLabel": "Equity Component"
       }
      }
     },
     "localname": "EquityComponentDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EquityInterestIssuedOrIssuableByTypeAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of equity interests that are issued or issuable in a business combination.",
        "label": "Equity Interest Issued Or Issuable By Type [Axis]",
        "terseLabel": "Equity Interest Type"
       }
      }
     },
     "localname": "EquityInterestIssuedOrIssuableByTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EquityInterestIssuedOrIssuableTypeDomain": {
     "auth_ref": [
      "r341"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Name of equity interest issued or issuable to acquire an entity in a business combination.",
        "label": "Equity Interest Issued Or Issuable Type [Domain]",
        "terseLabel": "Equity Interest Issued or Issuable, Type"
       }
      }
     },
     "localname": "EquityInterestIssuedOrIssuableTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EquitySecuritiesFvNi": {
     "auth_ref": [
      "r407"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails": {
       "order": 10040.0,
       "parentTag": "us-gaap_AssetsFairValueDisclosure",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).",
        "label": "Equity Securities Fv Ni",
        "terseLabel": "Securities carried at fair value with changes recorded in net income",
        "verboseLabel": "Equity securities"
       }
      }
     },
     "localname": "EquitySecuritiesFvNi",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EquitySecuritiesFvNiCost": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value.",
        "label": "Equity Securities Fv Ni Cost",
        "verboseLabel": "Equity securities carried at fair value with changes recorded in net income, amortized cost"
       }
      }
     },
     "localname": "EquitySecuritiesFvNiCost",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EquitySecuritiesFvNiUnrealizedLoss": {
     "auth_ref": [
      "r200"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of unrealized loss on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).",
        "label": "Equity Securities Fv Ni Unrealized Loss",
        "terseLabel": "Equity securities carried at fair value with changes recorded in net income, unrealized losses"
       }
      }
     },
     "localname": "EquitySecuritiesFvNiUnrealizedLoss",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EquitySecuritiesMember": {
     "auth_ref": [
      "r17",
      "r19",
      "r198",
      "r457",
      "r513",
      "r533"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Ownership interest or right to acquire or dispose of ownership interest in corporations and other legal entities for which ownership interest is represented by shares of common or preferred stock, convertible securities, stock rights, or stock warrants.",
        "label": "Equity Securities [Member]",
        "terseLabel": "Equity securities"
       }
      }
     },
     "localname": "EquitySecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount": {
     "auth_ref": [
      "r199"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in equity security without readily determinable fair value.",
        "label": "Equity Securities Without Readily Determinable Fair Value Amount",
        "terseLabel": "Non-marketable investments without readily determinable fair values"
       }
      }
     },
     "localname": "EquitySecuritiesWithoutReadilyDeterminableFairValueAmount",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EstimateOfFairValueFairValueDisclosureMember": {
     "auth_ref": [
      "r409"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measured as an estimate of fair value.",
        "label": "Estimate Of Fair Value Fair Value Disclosure [Member]",
        "terseLabel": "Fair Value",
        "verboseLabel": "Fair Value"
       }
      }
     },
     "localname": "EstimateOfFairValueFairValueDisclosureMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ExcessTangibleCapitalRequiredForCapitalAdequacyToTangibleAssets": {
     "auth_ref": [
      "r502"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of excess Tangible Capital, which generally includes outstanding stock plus retained earnings, divided by tangible assets (assets with physical existence) as defined in the regulations.",
        "label": "Excess Tangible Capital Required For Capital Adequacy To Tangible Assets",
        "terseLabel": "BHC and PCA Well-Capitalized"
       }
      }
     },
     "localname": "ExcessTangibleCapitalRequiredForCapitalAdequacyToTangibleAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]",
        "terseLabel": "Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable": {
     "auth_ref": [
      "r391",
      "r392",
      "r393",
      "r404"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about asset and liability measured at fair value on recurring and nonrecurring basis.",
        "label": "Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table]",
        "terseLabel": "Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table]"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about input and valuation technique used to measure fair value and change in valuation approach and technique for each separate class of asset and liability measured on recurring and nonrecurring basis.",
        "label": "Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Table]",
        "terseLabel": "Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Table]"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of input and valuation technique used to measure fair value and change in valuation approach and technique for each separate class of asset and liability measured on recurring and nonrecurring basis.",
        "label": "Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques Table [Text Block]",
        "terseLabel": "Quantitative Information about Level 3 Fair Value Measurements-Recurring"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisGainLossIncludedInEarningsTextBlock": {
     "auth_ref": [
      "r398",
      "r401"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the amount of gains or losses for the period included in earnings or resulted in a change to net assets, have arisen from the use of significant unobservable inputs (level 3) to measure the fair value of assets, liabilities, and financial instruments classified in shareholders' equity.",
        "label": "Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Text Block]",
        "terseLabel": "Changes in Estimated Fair Value for Financial Assets and Liabilities Measured on Recurring Basis"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisGainLossIncludedInEarningsTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueAssetsMeasuredOnNonrecurringBasisTextBlock": {
     "auth_ref": [
      "r391",
      "r392",
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of assets and liabilities by class, including financial instruments measured at fair value that are classified in shareholders' equity, if any, that are measured at fair value on a nonrecurring basis in periods after initial recognition (for example, impaired assets). Disclosures may include, but are not limited to: (a) the fair value measurements recorded and the reasons for the measurements and (b) the level within the fair value hierarchy in which the fair value measurements are categorized in their entirety (levels 1, 2, 3).",
        "label": "Fair Value Assets Measured On Nonrecurring Basis [Text Block]",
        "terseLabel": "Carrying Value of Assets Measured at Fair Value on a Non-Recurring Basis"
       }
      }
     },
     "localname": "FairValueAssetsMeasuredOnNonrecurringBasisTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain": {
     "auth_ref": [
      "r397"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Class of asset.",
        "label": "Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation By Asset Class [Domain]",
        "terseLabel": "Asset Class"
       }
      }
     },
     "localname": "FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.",
        "label": "Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation Calculation Roll Forward",
        "terseLabel": "Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]"
       }
      }
     },
     "localname": "FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]",
        "terseLabel": "Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]"
       }
      }
     },
     "localname": "FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByAssetClassAxis": {
     "auth_ref": [
      "r391",
      "r404"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by class of asset.",
        "label": "Fair Value By Asset Class [Axis]",
        "terseLabel": "Asset Class"
       }
      }
     },
     "localname": "FairValueByAssetClassAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByBalanceSheetGroupingTable": {
     "auth_ref": [
      "r391",
      "r410",
      "r411"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about the fair value of financial instruments, including financial assets and financial liabilities, and the measurements of those instruments, assets, and liabilities.",
        "label": "Fair Value By Balance Sheet Grouping [Table]",
        "terseLabel": "Fair Value By Balance Sheet Grouping [Table]"
       }
      }
     },
     "localname": "FairValueByBalanceSheetGroupingTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByBalanceSheetGroupingTextBlock": {
     "auth_ref": [
      "r391",
      "r410"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the fair value of financial instruments, including financial assets and financial liabilities, and the measurements of those instruments, assets, and liabilities.",
        "label": "Fair Value By Balance Sheet Grouping [Text Block]",
        "terseLabel": "Carrying and Estimated Fair Values of Financial Instruments"
       }
      }
     },
     "localname": "FairValueByBalanceSheetGroupingTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueByFairValueHierarchyLevelAxis": {
     "auth_ref": [
      "r311",
      "r312",
      "r315",
      "r392",
      "r438"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by level within fair value hierarchy and fair value measured at net asset value per share as practical expedient.",
        "label": "Fair Value By Fair Value Hierarchy Level [Axis]",
        "terseLabel": "Fair Value Hierarchy and NAV"
       }
      }
     },
     "localname": "FairValueByFairValueHierarchyLevelAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByLiabilityClassAxis": {
     "auth_ref": [
      "r403",
      "r404"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by class of liability.",
        "label": "Fair Value By Liability Class [Axis]",
        "terseLabel": "Liability Class"
       }
      }
     },
     "localname": "FairValueByLiabilityClassAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByMeasurementBasisAxis": {
     "auth_ref": [
      "r391",
      "r405"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by measurement basis.",
        "label": "Fair Value By Measurement Basis [Axis]",
        "terseLabel": "Measurement Basis"
       }
      }
     },
     "localname": "FairValueByMeasurementBasisAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByMeasurementFrequencyAxis": {
     "auth_ref": [
      "r391",
      "r392",
      "r395",
      "r396",
      "r406"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by measurement frequency.",
        "label": "Fair Value By Measurement Frequency [Axis]",
        "terseLabel": "Measurement Frequency"
       }
      }
     },
     "localname": "FairValueByMeasurementFrequencyAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueDisclosureItemAmountsDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement basis, for example, but not limited to, reported value, fair value, portion at fair value, portion at other than fair value.",
        "label": "Fair Value Disclosure Item Amounts [Domain]",
        "terseLabel": "Fair Value Measurement"
       }
      }
     },
     "localname": "FairValueDisclosureItemAmountsDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueDisclosuresAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Fair Value Disclosures [Abstract]"
       }
      }
     },
     "localname": "FairValueDisclosuresAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueDisclosuresTextBlock": {
     "auth_ref": [
      "r403"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.",
        "label": "Fair Value Disclosures [Text Block]",
        "terseLabel": "Fair Value"
       }
      }
     },
     "localname": "FairValueDisclosuresTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValue"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueHedgeAssetsAtFairValue": {
     "auth_ref": [
      "r372"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails": {
       "order": 10050.0,
       "parentTag": "us-gaap_AssetsFairValueDisclosure",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of all derivative assets designated as fair value hedging instruments.",
        "label": "Fair Value Hedge Assets At Fair Value",
        "terseLabel": "Total derivative assets at fair value \u2014 non-qualifying hedges"
       }
      }
     },
     "localname": "FairValueHedgeAssetsAtFairValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueHedgeLiabilitiesAtFairValue": {
     "auth_ref": [
      "r372"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_LiabilitiesFairValueDisclosure",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of all derivative liabilities designated as fair value hedging instruments.",
        "label": "Fair Value Hedge Liabilities At Fair Value",
        "negatedLabel": "Total derivative liabilities at fair value \u2014 non-qualifying hedges"
       }
      }
     },
     "localname": "FairValueHedgeLiabilitiesAtFairValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueHedgingMember": {
     "auth_ref": [
      "r365"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A hedge of the exposure to changes in the fair value of a recognized asset or liability, or of an unrecognized firm commitment, that are attributable to a particular risk.",
        "label": "Fair Value Hedging [Member]",
        "terseLabel": "Fair Value Hedges"
       }
      }
     },
     "localname": "FairValueHedgingMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueInputsLevel1Member": {
     "auth_ref": [
      "r311",
      "r312",
      "r315",
      "r392",
      "r439"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Quoted prices in active markets for identical assets or liabilities that the reporting entity can access at the measurement date.",
        "label": "Fair Value Inputs Level1 [Member]",
        "terseLabel": "Level 1"
       }
      }
     },
     "localname": "FairValueInputsLevel1Member",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueInputsLevel2Member": {
     "auth_ref": [
      "r311",
      "r312",
      "r315",
      "r392",
      "r440"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Inputs other than quoted prices included within level 1 that are observable for an asset or liability, either directly or indirectly, including, but not limited to, quoted prices for similar assets or liabilities in active markets, or quoted prices for identical or similar assets or liabilities in inactive markets.",
        "label": "Fair Value Inputs Level2 [Member]",
        "terseLabel": "Level 2"
       }
      }
     },
     "localname": "FairValueInputsLevel2Member",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueInputsLevel3Member": {
     "auth_ref": [
      "r311",
      "r312",
      "r315",
      "r392",
      "r441"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.",
        "label": "Fair Value Inputs Level3 [Member]",
        "terseLabel": "Level 3"
       }
      }
     },
     "localname": "FairValueInputsLevel3Member",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain": {
     "auth_ref": [
      "r397"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Represents classes of liabilities measured and disclosed at fair value.",
        "label": "Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation By Liability Class [Domain]",
        "terseLabel": "Fair Value by Liability Class"
       }
      }
     },
     "localname": "FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.",
        "label": "Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation Roll Forward",
        "terseLabel": "Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]"
       }
      }
     },
     "localname": "FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueMeasurementFrequencyDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement frequency.",
        "label": "Fair Value Measurement Frequency [Domain]",
        "terseLabel": "Measurement Frequency"
       }
      }
     },
     "localname": "FairValueMeasurementFrequencyDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1": {
     "auth_ref": [
      "r398"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).",
        "label": "Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1",
        "terseLabel": "Included in earnings"
       }
      }
     },
     "localname": "FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss": {
     "auth_ref": [
      "r399"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).",
        "label": "Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss",
        "terseLabel": "Included in comprehensive income"
       }
      }
     },
     "localname": "FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements": {
     "auth_ref": [
      "r400"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.",
        "label": "Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements",
        "negatedLabel": "Sales, paydowns, and adjustments"
       }
      }
     },
     "localname": "FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue": {
     "auth_ref": [
      "r397"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.",
        "label": "Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value",
        "periodEndLabel": "Ending Balance",
        "periodStartLabel": "Beginning Balance"
       }
      }
     },
     "localname": "FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings": {
     "auth_ref": [
      "r398"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).",
        "label": "Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Included In Earnings",
        "negatedLabel": "Included in earnings"
       }
      }
     },
     "localname": "FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome": {
     "auth_ref": [
      "r399"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of gain (loss) recognized in other comprehensive income (OCI) from liability measured at fair value on recurring basis using unobservable input (level 3).",
        "label": "Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Included In Other Comprehensive Income",
        "negatedLabel": "Included in comprehensive income"
       }
      }
     },
     "localname": "FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue": {
     "auth_ref": [
      "r397"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.",
        "label": "Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value",
        "negatedPeriodEndLabel": "Ending Balance",
        "negatedPeriodStartLabel": "Beginning Balance"
       }
      }
     },
     "localname": "FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueChangesInEstimatedFairValueForFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementsFairValueHierarchyDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Categories used to prioritize the inputs to valuation techniques to measure fair value.",
        "label": "Fair Value Measurements Fair Value Hierarchy [Domain]",
        "terseLabel": "Fair Value Hierarchy and NAV"
       }
      }
     },
     "localname": "FairValueMeasurementsFairValueHierarchyDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueMeasurementsNonrecurringMember": {
     "auth_ref": [
      "r391",
      "r392",
      "r395",
      "r396",
      "r402",
      "r406"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Infrequent fair value measurement. Includes, but is not limited to, fair value adjustment for impairment of asset, liability or equity, not frequently measured at fair value.",
        "label": "Fair Value Measurements Nonrecurring [Member]",
        "terseLabel": "Non-Recurring"
       }
      }
     },
     "localname": "FairValueMeasurementsNonrecurringMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueMeasurementsRecurringMember": {
     "auth_ref": [
      "r403",
      "r406"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Frequent fair value measurement. Includes, but is not limited to, fair value adjustment for impairment of asset, liability or equity, frequently measured at fair value.",
        "label": "Fair Value Measurements Recurring [Member]",
        "terseLabel": "Recurring"
       }
      }
     },
     "localname": "FairValueMeasurementsRecurringMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds": {
     "auth_ref": [
      "r35",
      "r462",
      "r493"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).",
        "label": "Federal Home Loan Bank Advances General Debt Obligations Disclosures Amount Of Available Unused Funds",
        "terseLabel": "FHLB advances, unused and available",
        "totalLabel": "Available capacity"
       }
      }
     },
     "localname": "FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1": {
     "auth_ref": [
      "r493",
      "r497"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of the collateral pledged in support of federal home loan bank advances outstanding.",
        "label": "Federal Home Loan Bank Advances General Debt Obligations Disclosures Collateral Pledged1",
        "terseLabel": "Pledged assets"
       }
      }
     },
     "localname": "FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresInterestRateAtPeriodEnd": {
     "auth_ref": [
      "r493",
      "r496"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "States the interest rate applicable to Federal Home Loan Bank advances outstanding as of the Balance Sheet date.",
        "label": "Federal Home Loan Bank Advances General Debt Obligations Disclosures Interest Rate At Period End",
        "terseLabel": "FHLB advances, weighted average percentage rates"
       }
      }
     },
     "localname": "FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresInterestRateAtPeriodEnd",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable": {
     "auth_ref": [
      "r35",
      "r462",
      "r493"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of maximum advances or credit lines available from the Federal Home Loan Bank (FHLB).",
        "label": "Federal Home Loan Bank Advances General Debt Obligations Disclosures Maximum Amount Available",
        "terseLabel": "FHLB advances, financing availability"
       }
      }
     },
     "localname": "FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FederalHomeLoanBankAdvancesLongTerm": {
     "auth_ref": [
      "r465",
      "r493",
      "r495"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.",
        "label": "Federal Home Loan Bank Advances Long Term",
        "negatedLabel": "Advances",
        "terseLabel": "FHLB advances"
       }
      }
     },
     "localname": "FederalHomeLoanBankAdvancesLongTerm",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FederalHomeLoanBankAdvancesMember": {
     "auth_ref": [
      "r462"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Borrowings from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and also in times of liquidity shortages. The member institution executes a promissory note, which is generally collateralized by government securities to the Federal Reserve or loans.",
        "label": "Federal Home Loan Bank Advances [Member]",
        "terseLabel": "FHLB advances"
       }
      }
     },
     "localname": "FederalHomeLoanBankAdvancesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FederalHomeLoanBankStockAndFederalReserveBankStock": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of Federal Home Loan Bank (FHLB) and Federal Reserve Bank stock.",
        "label": "Federal Home Loan Bank Stock And Federal Reserve Bank Stock",
        "terseLabel": "Restricted Stock of FRB and FHLB"
       }
      }
     },
     "localname": "FederalHomeLoanBankStockAndFederalReserveBankStock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FederalReserveBankAdvancesMember": {
     "auth_ref": [
      "r462"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Borrowings from the Federal Reserve Bank, which are primarily used to cover shortages in the required reserve balance and also in times of liquidity shortages.",
        "label": "Federal Reserve Bank Advances [Member]",
        "terseLabel": "Federal Reserve System (\"FRB\")"
       }
      }
     },
     "localname": "FederalReserveBankAdvancesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinanceLoanAndLeaseReceivablesHeldForInvestmentAllowanceAndNonperformingLoansPolicy": {
     "auth_ref": [
      "r109",
      "r146",
      "r168",
      "r173",
      "r459"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Describes an entity's accounting policy and methodology for estimating its allowance for loan and lease losses, and its accounting policy for nonperforming loans. The description identifies the factors that influenced management of the entity in establishing the level of the allowance (for example, historical losses and existing economic conditions) and also may include discussion of the risk elements relevant to particular categories of receivables. The disclosure also may describe any liability the entity has recorded for off-balance sheet credit losses and may include the basis for determining each element of the allowance for loan and lease losses. The disclosure also could discuss the entity's policy for (1) placing loans on nonaccrual status (or discontinuing accrual of interest) and recording payments received on nonaccrual loans, and the policy for resuming accrual of interest, (2) charging-off uncollectible loans, and (3) determining past due or delinquency status (that is, whether past due status is based on how recently payments have been received or contractual terms).",
        "label": "Finance Loan And Lease Receivables Held For Investment Allowance And Nonperforming Loans Policy",
        "terseLabel": "Allowance Methodology"
       }
      }
     },
     "localname": "FinanceLoanAndLeaseReceivablesHeldForInvestmentAllowanceAndNonperformingLoansPolicy",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FinanceReceivablesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amounts due the Company from customers, clients, lessees, borrowers, or others under the terms of its agreements therewith. Such amount may include accrued interest receivable in accordance with the terms of the agreements. The agreements also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among myriad other features and characteristics.",
        "label": "Finance Receivables [Member]",
        "terseLabel": "Financing Leases and Leverage Leases"
       }
      }
     },
     "localname": "FinanceReceivablesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancialAssetAcquiredWithCreditDeteriorationMember": {
     "auth_ref": [
      "r179"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financial asset acquired with deteriorated credit quality.",
        "label": "Financial Asset Acquired With Credit Deterioration [Member]",
        "terseLabel": "PCI Loans",
        "verboseLabel": "PCD Loans"
       }
      }
     },
     "localname": "FinancialAssetAcquiredWithCreditDeteriorationMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansInProcessOfForeclosureParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancialInstrumentAxis": {
     "auth_ref": [
      "r209",
      "r216",
      "r217",
      "r222",
      "r228",
      "r243",
      "r245",
      "r246",
      "r247"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of financial instrument.",
        "label": "Financial Instrument [Axis]",
        "terseLabel": "Financial Instrument"
       }
      }
     },
     "localname": "FinancialInstrumentAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfModificationsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Financial Instruments Financial Assets Balance Sheet Groupings [Abstract]",
        "terseLabel": "Financial Assets"
       }
      }
     },
     "localname": "FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Financial Instruments Financial Liabilities Balance Sheet Groupings [Abstract]",
        "terseLabel": "Financial Liabilities"
       }
      }
     },
     "localname": "FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableAfterDeferredIncomeOffset": {
     "auth_ref": [
      "r167",
      "r227",
      "r239",
      "r240"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10240.0,
       "parentTag": "us-gaap_NotesReceivableNet",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after fee received for commitment to originate or purchase, of financing receivable. Excludes financing receivable covered under loss sharing agreement.",
        "label": "Financing Receivable After Deferred Income Offset",
        "periodEndLabel": "Ending balance",
        "positiveLabel": "Loans",
        "positiveVerboseLabel": "Total",
        "terseLabel": "Loans (see Note 9 for amounts pledged)",
        "totalLabel": "Loans",
        "verboseLabel": "Total loans"
       }
      }
     },
     "localname": "FinancingReceivableAfterDeferredIncomeOffset",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Financing Receivable Allowance For Credit Loss Additional Information [Abstract]",
        "terseLabel": "Allowance balance"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease": {
     "auth_ref": [
      "r212"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase in allowance for credit loss on financing receivable purchased with credit deterioration.",
        "label": "Financing Receivable Allowance For Credit Loss Purchased With Credit Deterioration Increase",
        "terseLabel": "Net impact of additional PCD reserves"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLosses": {
     "auth_ref": [
      "r147",
      "r207",
      "r210",
      "r215",
      "r458"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10250.0,
       "parentTag": "us-gaap_NotesReceivableNet",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.",
        "label": "Financing Receivable Allowance For Credit Losses",
        "negatedLabel": "Allowance for credit losses",
        "periodEndLabel": "Allowance balance - end of period",
        "periodStartLabel": "Beginning balance",
        "terseLabel": "Allowance for credit losses"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLosses",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment": {
     "auth_ref": [
      "r151"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.",
        "label": "Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment",
        "terseLabel": "Loans collectively evaluated for impairment"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1": {
     "auth_ref": [
      "r151"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.",
        "label": "Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1",
        "periodStartLabel": "Loans individually evaluated for impairment"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Financing Receivable Allowance For Credit Losses [Line Items]",
        "terseLabel": "Financing Receivable Allowance For Credit Losses [Line Items]"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossesLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery": {
     "auth_ref": [
      "r150",
      "r214",
      "r239",
      "r458"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of recovery of financing receivables doubtful of collection that were previously charged off.",
        "label": "Financing Receivable Allowance For Credit Losses Recovery",
        "terseLabel": "Recoveries"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossesRecovery",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.",
        "label": "Financing Receivable Allowance For Credit Losses Roll Forward",
        "terseLabel": "Financing Receivable, Allowance for Credit Losses [Roll Forward]"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossesRollForward",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs": {
     "auth_ref": [
      "r149",
      "r213",
      "r239",
      "r458"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of writeoff of financing receivable, charged against allowance for credit loss.",
        "label": "Financing Receivable Allowance For Credit Losses Write Offs",
        "negatedLabel": "Gross charge-offs",
        "terseLabel": "Gross charge-offs",
        "verboseLabel": "Loans charged-off"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossesWriteOffs",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment": {
     "auth_ref": [
      "r152"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The balance of financing receivables that were collectively evaluated for impairment.",
        "label": "Financing Receivable Collectively Evaluated For Impairment",
        "terseLabel": "Loans collectively evaluated for impairment"
       }
      }
     },
     "localname": "FinancingReceivableCollectivelyEvaluatedForImpairment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableCreditQualityIndicatorsTableTextBlock": {
     "auth_ref": [
      "r162",
      "r228"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of financing receivables by credit quality indicator. The credit quality indicator is a statistic about the credit quality of financing receivables. Examples include, but not limited to, consumer credit risk scores, credit-rating-agency ratings, an entity's internal credit risk grades, loan-to-value ratios, collateral, collection experience and other internal metrics.",
        "label": "Financing Receivable Credit Quality Indicators Table [Text Block]",
        "terseLabel": "Loans - By Risk Rating"
       }
      }
     },
     "localname": "FinancingReceivableCreditQualityIndicatorsTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FinancingReceivableImpairedLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Financing Receivable Impaired [Line Items]",
        "terseLabel": "Financing Receivable Impaired [Line Items]"
       }
      }
     },
     "localname": "FinancingReceivableImpairedLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment": {
     "auth_ref": [
      "r152"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The balance of financing receivables that were individually evaluated for impairment.",
        "label": "Financing Receivable Individually Evaluated For Impairment",
        "verboseLabel": "Loans individually evaluated for impairment"
       }
      }
     },
     "localname": "FinancingReceivableIndividuallyEvaluatedForImpairment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableModificationsRecordedInvestment": {
     "auth_ref": [
      "r164",
      "r181"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable modified as troubled debt restructuring.",
        "label": "Financing Receivable Modifications Recorded Investment",
        "terseLabel": "Recorded Investment"
       }
      }
     },
     "localname": "FinancingReceivableModificationsRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfTdrsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableNonaccrualInterestIncome": {
     "auth_ref": [
      "r219"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of interest income on financing receivable on nonaccrual status.",
        "label": "Financing Receivable Nonaccrual Interest Income",
        "terseLabel": "Interest on non-accrual loan"
       }
      }
     },
     "localname": "FinancingReceivableNonaccrualInterestIncome",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableNonaccrualNoAllowance": {
     "auth_ref": [
      "r221"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable on nonaccrual status with no allowance for credit loss.",
        "label": "Financing Receivable Nonaccrual No Allowance",
        "terseLabel": "Total non-accrual, With No Allowance Recorded"
       }
      }
     },
     "localname": "FinancingReceivableNonaccrualNoAllowance",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableOriginatedFiveOrMoreYearsBeforeLatestFiscalYear": {
     "auth_ref": [
      "r229",
      "r239"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails": {
       "order": 10060.0,
       "parentTag": "us-gaap_FinancingReceivableAfterDeferredIncomeOffset",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable originated five or more years prior to latest fiscal year.",
        "label": "Financing Receivable Originated Five Or More Years Before Latest Fiscal Year",
        "terseLabel": "2015 &amp; Prior"
       }
      }
     },
     "localname": "FinancingReceivableOriginatedFiveOrMoreYearsBeforeLatestFiscalYear",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableOriginatedFourYearsBeforeLatestFiscalYear": {
     "auth_ref": [
      "r229",
      "r239"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails": {
       "order": 10050.0,
       "parentTag": "us-gaap_FinancingReceivableAfterDeferredIncomeOffset",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable originated four years prior to latest fiscal year.",
        "label": "Financing Receivable Originated Four Years Before Latest Fiscal Year",
        "terseLabel": "2016"
       }
      }
     },
     "localname": "FinancingReceivableOriginatedFourYearsBeforeLatestFiscalYear",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableOriginatedInCurrentFiscalYear": {
     "auth_ref": [
      "r229",
      "r239"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_FinancingReceivableAfterDeferredIncomeOffset",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable originated in current fiscal year.",
        "label": "Financing Receivable Originated In Current Fiscal Year",
        "terseLabel": "2020"
       }
      }
     },
     "localname": "FinancingReceivableOriginatedInCurrentFiscalYear",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear": {
     "auth_ref": [
      "r229",
      "r239"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_FinancingReceivableAfterDeferredIncomeOffset",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable originated in fiscal year prior to latest fiscal year.",
        "label": "Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year",
        "terseLabel": "2019"
       }
      }
     },
     "localname": "FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear": {
     "auth_ref": [
      "r229",
      "r239"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails": {
       "order": 10040.0,
       "parentTag": "us-gaap_FinancingReceivableAfterDeferredIncomeOffset",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable originated three years prior to latest fiscal year.",
        "label": "Financing Receivable Originated Three Years Before Latest Fiscal Year",
        "terseLabel": "2017"
       }
      }
     },
     "localname": "FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear": {
     "auth_ref": [
      "r229",
      "r239"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_FinancingReceivableAfterDeferredIncomeOffset",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable originated two years prior to latest fiscal year.",
        "label": "Financing Receivable Originated Two Years Before Latest Fiscal Year",
        "terseLabel": "2018"
       }
      }
     },
     "localname": "FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivablePortfolioSegmentAxis": {
     "auth_ref": [
      "r209",
      "r216",
      "r230"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by the level at which an entity develops and documents a systematic methodology to determine its allowance for credit losses.",
        "label": "Financing Receivable Portfolio Segment [Axis]",
        "terseLabel": "Financing Receivable Portfolio Segment"
       }
      }
     },
     "localname": "FinancingReceivablePortfolioSegmentAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfTdrsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivablePortfolioSegmentDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Level at which an entity develops and documents a systematic methodology to determine its allowance for credit losses.",
        "label": "Financing Receivable Portfolio Segment [Domain]",
        "terseLabel": "Financing Receivable Portfolio Segment"
       }
      }
     },
     "localname": "FinancingReceivablePortfolioSegmentDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfTdrsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate": {
     "auth_ref": [
      "r224"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of allowance for credit loss at acquisition date of financing receivable purchased with credit deterioration.",
        "label": "Financing Receivable Purchased With Credit Deterioration Allowance For Credit Loss At Acquisition Date",
        "negatedLabel": "Allowance for Credit Losses",
        "verboseLabel": "Initial ACL recognized on PCD assets"
       }
      }
     },
     "localname": "FinancingReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtParValue": {
     "auth_ref": [
      "r226"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount at par value of financing receivable purchased with credit deterioration.",
        "label": "Financing Receivable Purchased With Credit Deterioration Amount At Par Value",
        "terseLabel": "Par Value (UPB)"
       }
      }
     },
     "localname": "FinancingReceivablePurchasedWithCreditDeteriorationAmountAtParValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice": {
     "auth_ref": [
      "r223"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount at purchase price of financing receivable purchased with credit deterioration.",
        "label": "Financing Receivable Purchased With Credit Deterioration Amount At Purchase Price",
        "totalLabel": "Purchase Price"
       }
      }
     },
     "localname": "FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationDiscountPremium": {
     "auth_ref": [
      "r225"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of discount (premium) attributable to other factors on financing receivable purchased with credit deterioration.",
        "label": "Financing Receivable Purchased With Credit Deterioration Discount Premium",
        "negatedLabel": "(Discount) Premium"
       }
      }
     },
     "localname": "FinancingReceivablePurchasedWithCreditDeteriorationDiscountPremium",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing": {
     "auth_ref": [
      "r170",
      "r220",
      "r240"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable 90 days or more past due and still accruing.",
        "label": "Financing Receivable Recorded Investment90 Days Past Due And Still Accruing",
        "terseLabel": "Total accruing loans past due 90 days or more",
        "verboseLabel": "90 days or more past due loans"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis": {
     "auth_ref": [
      "r163",
      "r171",
      "r172",
      "r217",
      "r222",
      "r228",
      "r231",
      "r232",
      "r239",
      "r240"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by class of financing receivable determined on the basis of initial measurement attribute, risk characteristics and method of monitoring and assessing credit risk.",
        "label": "Financing Receivable Recorded Investment By Class Of Financing Receivable [Axis]",
        "terseLabel": "Class of Financing Receivable"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing receivables determined on the basis of initial measurement attribute, risk characteristics and method of monitoring and assessing credit risk.",
        "label": "Financing Receivable Recorded Investment Class Of Financing Receivable [Domain]",
        "terseLabel": "Class of Financing Receivable"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestmentCurrent": {
     "auth_ref": [
      "r217",
      "r240"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable not past due.",
        "label": "Financing Receivable Recorded Investment Current",
        "terseLabel": "Current"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentCurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestmentLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Financing Receivable Recorded Investment [Line Items]",
        "terseLabel": "Financing Receivable, Recorded Investment [Line Items]"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus": {
     "auth_ref": [
      "r169",
      "r218"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails": {
       "order": 10010.0,
       "parentTag": "cit_TotalNonPerformingAssets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable on nonaccrual status.",
        "label": "Financing Receivable Recorded Investment Nonaccrual Status",
        "positiveLabel": "Non-accrual loans",
        "terseLabel": "Total non-accrual loans"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentNonaccrualStatus",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestmentPastDue": {
     "auth_ref": [
      "r172",
      "r217",
      "r240"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable past due.",
        "label": "Financing Receivable Recorded Investment Past Due",
        "terseLabel": "Total Past Due",
        "verboseLabel": "Total past due"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentPastDue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Financing Receivable Recorded Investment Past Due [Line Items]",
        "terseLabel": "Financing Receivable, Recorded Investment, Past Due [Line Items]"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentPastDueLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableRevolving": {
     "auth_ref": [
      "r229",
      "r239"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails": {
       "order": 10070.0,
       "parentTag": "us-gaap_FinancingReceivableAfterDeferredIncomeOffset",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable that can be withdrawn, repaid and redrawn.",
        "label": "Financing Receivable Revolving",
        "terseLabel": "Revolving Loans Amortized Cost Basis"
       }
      }
     },
     "localname": "FinancingReceivableRevolving",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableThresholdPeriodPastDueWriteoff": {
     "auth_ref": [
      "r217"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Threshold period for when financing receivable is considered past due to write off as uncollectible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.",
        "label": "Financing Receivable Threshold Period Past Due Writeoff",
        "terseLabel": "Delinquency period for loan charge offs"
       }
      }
     },
     "localname": "FinancingReceivableThresholdPeriodPastDueWriteoff",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_FinancingReceivables30To59DaysPastDueMember": {
     "auth_ref": [
      "r240"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financial asset more than 29 days past due but fewer than 60 days past due.",
        "label": "Financing Receivables30 To59 Days Past Due [Member]",
        "terseLabel": "30-59 Past Due"
       }
      }
     },
     "localname": "FinancingReceivables30To59DaysPastDueMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancingReceivables60To89DaysPastDueMember": {
     "auth_ref": [
      "r240"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financial asset more than 59 days past due but fewer than 90 days past due.",
        "label": "Financing Receivables60 To89 Days Past Due [Member]",
        "terseLabel": "60-89 Past Due"
       }
      }
     },
     "localname": "FinancingReceivables60To89DaysPastDueMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember": {
     "auth_ref": [
      "r240"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financial asset equal to or greater than 90 days past due.",
        "label": "Financing Receivables Equal To Greater Than90 Days Past Due [Member]",
        "terseLabel": "90 or more Past Due"
       }
      }
     },
     "localname": "FinancingReceivablesEqualToGreaterThan90DaysPastDueMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancingReceivablesPeriodPastDueAxis": {
     "auth_ref": [
      "r217",
      "r240"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by time period financial asset is past due.",
        "label": "Financing Receivables Period Past Due [Axis]",
        "terseLabel": "Financial Asset, Period Past Due"
       }
      }
     },
     "localname": "FinancingReceivablesPeriodPastDueAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivablesPeriodPastDueDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Period in which financial asset is past due. Element name and standard label in Financial Asset, [numeric lower end] to [numeric higher end] [date measure] Past Due [Member] or Financial Asset, Greater Than [low end numeric value] [date measure] Past Due [Member] or Financial Asset, Less Than [high end numeric value] [date measure] Past Due [Member] formats.",
        "label": "Financing Receivables Period Past Due [Domain]",
        "terseLabel": "Financial Asset, Period Past Due"
       }
      }
     },
     "localname": "FinancingReceivablesPeriodPastDueDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of finite-lived and indefinite-lived intangible assets acquired as part of a business combination.",
        "label": "Finite Lived And Indefinite Lived Intangible Assets Acquired As Part Of Business Combination Table [Text Block]",
        "terseLabel": "Summary of Intangible Assets Recorded in Conjunction with MOB Transaction"
       }
      }
     },
     "localname": "FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetUsefulLife": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.",
        "label": "Finite Lived Intangible Asset Useful Life",
        "terseLabel": "Estimated useful life",
        "verboseLabel": "Intangible assets, Estimated Useful Life"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetUsefulLife",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization": {
     "auth_ref": [
      "r264"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_FiniteLivedIntangibleAssetsNet",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.",
        "label": "Finite Lived Intangible Assets Accumulated Amortization",
        "negatedLabel": "Accumulated Amortization",
        "terseLabel": "Accumulated amortization"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsAccumulatedAmortization",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Finite Lived Intangible Assets Amortization Expense Remainder Of Fiscal Year",
        "terseLabel": "Projected amortization for 2021"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive": {
     "auth_ref": [
      "r266"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Finite Lived Intangible Assets Amortization Expense Year Five",
        "terseLabel": "Projected amortization for 2025"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsAmortizationExpenseYearFive",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour": {
     "auth_ref": [
      "r266"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Finite Lived Intangible Assets Amortization Expense Year Four",
        "terseLabel": "Projected amortization for 2024"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsAmortizationExpenseYearFour",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree": {
     "auth_ref": [
      "r266"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Finite Lived Intangible Assets Amortization Expense Year Three",
        "terseLabel": "Projected amortization for 2023"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsAmortizationExpenseYearThree",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo": {
     "auth_ref": [
      "r266"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Finite Lived Intangible Assets Amortization Expense Year Two",
        "terseLabel": "Projected amortization for 2022"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsAmortizationMethod": {
     "auth_ref": [
      "r258"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amortization method of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar either by their nature or by their use in the operations of a company. The straight-line method is the preferred amortization method, unless another method better reflects the pattern in which the asset is consumed.",
        "label": "Finite Lived Intangible Assets Amortization Method",
        "terseLabel": "Intangible assets, Amortization Method"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsAmortizationMethod",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis": {
     "auth_ref": [
      "r260",
      "r262",
      "r264",
      "r267",
      "r446"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by major type or class of finite-lived intangible assets.",
        "label": "Finite Lived Intangible Assets By Major Class [Axis]",
        "terseLabel": "Finite-Lived Intangible Assets by Major Class"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsByMajorClassAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsGross": {
     "auth_ref": [
      "r264",
      "r446"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_FiniteLivedIntangibleAssetsNet",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.",
        "label": "Finite Lived Intangible Assets Gross",
        "terseLabel": "Gross Carrying Amount"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsGross",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Finite Lived Intangible Assets [Line Items]",
        "terseLabel": "Finite Lived Intangible Assets [Line Items]"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfGoodwillDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain": {
     "auth_ref": [
      "r260",
      "r263"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The major class of finite-lived intangible asset (for example, patents, trademarks, copyrights, etc.) A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.",
        "label": "Finite Lived Intangible Assets Major Class Name [Domain]",
        "terseLabel": "Finite-Lived Intangible Assets, Major Class Name"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsMajorClassNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsNet": {
     "auth_ref": [
      "r264"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.",
        "label": "Finite Lived Intangible Assets Net",
        "periodEndLabel": "Intangible Assets, Ending Balance",
        "periodStartLabel": "Intangible Assets, Beginning Balance",
        "totalLabel": "Net Carrying Amount"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsNetAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Finite Lived Intangible Assets Net [Abstract]",
        "terseLabel": "Finite-Lived Intangible Assets, Net [Abstract]"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsNetAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsRollForward": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.",
        "label": "Finite Lived Intangible Assets Roll Forward",
        "terseLabel": "Finite-lived Intangible Assets [Roll Forward]"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsRollForward",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinitelivedIntangibleAssetsAcquired1": {
     "auth_ref": [
      "r261"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.",
        "label": "Finitelived Intangible Assets Acquired1",
        "terseLabel": "Intangible assets acquired",
        "verboseLabel": "Intangible assets, Fair Value"
       }
      }
     },
     "localname": "FinitelivedIntangibleAssetsAcquired1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ForeclosedAssets": {
     "auth_ref": [
      "r144",
      "r145"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails": {
       "order": 10020.0,
       "parentTag": "cit_TotalNonPerformingAssets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Carrying amount as of the balance sheet date of all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings or defeasance; includes real and personal property; equity interests in corporations, partnerships, and joint ventures; and beneficial interests in trusts.",
        "label": "Foreclosed Assets",
        "terseLabel": "Repossessed assets and OREO"
       }
      }
     },
     "localname": "ForeclosedAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ForeignCorporateDebtSecuritiesMember": {
     "auth_ref": [
      "r185",
      "r311"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt security issued by corporation not domiciled in United States of America (US).",
        "label": "Foreign Corporate Debt Securities [Member]",
        "terseLabel": "Corporate bonds - foreign",
        "verboseLabel": "Corporate bonds - foreign"
       }
      }
     },
     "localname": "ForeignCorporateDebtSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ForeignExchangeContractMember": {
     "auth_ref": [
      "r311",
      "r379"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative instrument whose primary underlying risk is tied to foreign exchange rates.",
        "label": "Foreign Exchange Contract [Member]",
        "terseLabel": "Foreign exchange contracts"
       }
      }
     },
     "localname": "ForeignExchangeContractMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ForeignExchangeForwardMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Foreign exchange forward traded on an exchange (examples include but are not limited to the International Securities Exchange, Philadelphia Stock Exchange, or the Chicago Mercantile Exchange) for options or future contracts to buy or sell a certain currency, at a specified date, at a fixed exercise exchange rate.",
        "label": "Foreign Exchange Forward [Member]",
        "terseLabel": "Foreign currency forward contracts"
       }
      }
     },
     "localname": "ForeignExchangeForwardMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_GainLossOnDerivativeInstrumentsNetPretax": {
     "auth_ref": [
      "r369"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.",
        "label": "Gain Loss On Derivative Instruments Net Pretax",
        "terseLabel": "Amounts recorded in Other Comprehensive Income"
       }
      }
     },
     "localname": "GainLossOnDerivativeInstrumentsNetPretax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GainLossOnFairValueHedgesRecognizedInEarnings": {
     "auth_ref": [
      "r374"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.",
        "label": "Gain Loss On Fair Value Hedges Recognized In Earnings",
        "terseLabel": "Net recognized on fair value hedges (No ineffectiveness)"
       }
      }
     },
     "localname": "GainLossOnFairValueHedgesRecognizedInEarnings",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges": {
     "auth_ref": [
      "r100"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10240.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of gain (loss) from the difference between the sale price or salvage price and the book value of an asset that was sold or retired, and gain (loss) from the write down of assets from their carrying value to fair value.",
        "label": "Gain Loss On Sales Of Assets And Asset Impairment Charges",
        "negatedLabel": "Net gain on asset sales and impairments on assets held for sale"
       }
      }
     },
     "localname": "GainLossOnSalesOfAssetsAndAssetImpairmentCharges",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GainsLossesOnExtinguishmentOfDebt": {
     "auth_ref": [
      "r100",
      "r297",
      "r298"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10170.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.",
        "label": "Gains Losses On Extinguishment Of Debt",
        "negatedLabel": "Loss on debt extinguishment and deposit redemption"
       }
      }
     },
     "localname": "GainsLossesOnExtinguishmentOfDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GeographicDistributionAxis": {
     "auth_ref": [
      "r233"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by geographic distribution of business activity identified as either domestic or foreign. Excludes names of countries, states and provinces, and cities.",
        "label": "Geographic Distribution [Axis]",
        "terseLabel": "Geographic Distribution"
       }
      }
     },
     "localname": "GeographicDistributionAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_GeographicDistributionDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Allocation of business activity identified as domestic or foreign. Excludes names of countries, states and provinces, and cities.",
        "label": "Geographic Distribution [Domain]",
        "terseLabel": "Geographic Distribution"
       }
      }
     },
     "localname": "GeographicDistributionDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_GeographicDistributionDomesticMember": {
     "auth_ref": [
      "r234"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Allocation of business activity identified as domestic.",
        "label": "Geographic Distribution Domestic [Member]",
        "terseLabel": "Domestic"
       }
      }
     },
     "localname": "GeographicDistributionDomesticMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_GeographicDistributionForeignMember": {
     "auth_ref": [
      "r235"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Allocation of business activity identified as foreign.",
        "label": "Geographic Distribution Foreign [Member]",
        "terseLabel": "Foreign"
       }
      }
     },
     "localname": "GeographicDistributionForeignMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_Goodwill": {
     "auth_ref": [
      "r249",
      "r251"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10220.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.",
        "label": "Goodwill",
        "periodEndLabel": "Ending Balance",
        "periodStartLabel": "Beginning Balance",
        "terseLabel": "Goodwill"
       }
      }
     },
     "localname": "Goodwill",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfGoodwillDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GoodwillAcquiredDuringPeriod": {
     "auth_ref": [
      "r252"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.",
        "label": "Goodwill Acquired During Period",
        "terseLabel": "Additions"
       }
      }
     },
     "localname": "GoodwillAcquiredDuringPeriod",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfGoodwillDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Goodwill And Intangible Assets Disclosure [Abstract]"
       }
      }
     },
     "localname": "GoodwillAndIntangibleAssetsDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock": {
     "auth_ref": [
      "r268"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for goodwill and intangible assets.",
        "label": "Goodwill And Intangible Assets Disclosure [Text Block]",
        "terseLabel": "GOODWILL AND INTANGIBLE ASSETS"
       }
      }
     },
     "localname": "GoodwillAndIntangibleAssetsDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssets"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_GoodwillImpairmentLoss": {
     "auth_ref": [
      "r100",
      "r250",
      "r253",
      "r256"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails": {
       "order": 10080.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": -1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10160.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.",
        "label": "Goodwill Impairment Loss",
        "negatedLabel": "Impairment",
        "terseLabel": "Goodwill impairment"
       }
      }
     },
     "localname": "GoodwillImpairmentLoss",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfGoodwillDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HedgingDesignationAxis": {
     "auth_ref": [
      "r367",
      "r383"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by designation of purpose of derivative instrument.",
        "label": "Hedging Designation [Axis]",
        "terseLabel": "Hedging Designation"
       }
      }
     },
     "localname": "HedgingDesignationAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_HedgingDesignationDomain": {
     "auth_ref": [
      "r367"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Designation of purpose of derivative instrument.",
        "label": "Hedging Designation [Domain]",
        "terseLabel": "Hedging Designation"
       }
      }
     },
     "localname": "HedgingDesignationDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_HedgingRelationshipDomain": {
     "auth_ref": [
      "r367"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Nature or intent of a hedge.",
        "label": "Hedging Relationship [Domain]",
        "terseLabel": "Hedging Relationship"
       }
      }
     },
     "localname": "HedgingRelationshipDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment": {
     "auth_ref": [
      "r159",
      "r161"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.",
        "label": "Impaired Financing Receivable Average Recorded Investment",
        "terseLabel": "Average Recorded Investment, total"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableAverageRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivablePolicyPolicyTextBlock": {
     "auth_ref": [
      "r154",
      "r158"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy for recognizing interest income on impaired financing receivables, including how cash receipts are recorded, the policy for determining which loans the entity assess for impairment, and the factors the creditor considered in determining that the financing receivable is impaired.",
        "label": "Impaired Financing Receivable Policy Policy [Text Block]",
        "terseLabel": "Individually Reviewed Loans"
       }
      }
     },
     "localname": "ImpairedFinancingReceivablePolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ImpairedFinancingReceivableRecordedInvestment": {
     "auth_ref": [
      "r155"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.",
        "label": "Impaired Financing Receivable Recorded Investment",
        "terseLabel": "Recorded investment, total",
        "verboseLabel": "Carrying Value"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableRelatedAllowance": {
     "auth_ref": [
      "r156"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of allowance for credit losses related to recorded investment.",
        "label": "Impaired Financing Receivable Related Allowance",
        "terseLabel": "Related Allowance",
        "verboseLabel": "Allowance for Loan Losses"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableRelatedAllowance",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance": {
     "auth_ref": [
      "r157"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.",
        "label": "Impaired Financing Receivable Unpaid Principal Balance",
        "terseLabel": "Unpaid principal balance, total",
        "verboseLabel": "Unpaid Principal Balance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableUnpaidPrincipalBalance",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment": {
     "auth_ref": [
      "r159",
      "r161"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of average investment of impaired financing receivables for which there is no related allowance for credit losses.",
        "label": "Impaired Financing Receivable With No Related Allowance Average Recorded Investment",
        "terseLabel": "With no related allowance, Average Recorded Investment"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment": {
     "auth_ref": [
      "r155"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.",
        "label": "Impaired Financing Receivable With No Related Allowance Recorded Investment",
        "terseLabel": "With no related allowance, Recorded Investment"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance": {
     "auth_ref": [
      "r157"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses.",
        "label": "Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance",
        "terseLabel": "With no related allowance, Unpaid Principal Balance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment": {
     "auth_ref": [
      "r159",
      "r161"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.",
        "label": "Impaired Financing Receivable With Related Allowance Average Recorded Investment",
        "terseLabel": "With related allowance, average recorded investment"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment": {
     "auth_ref": [
      "r155"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.",
        "label": "Impaired Financing Receivable With Related Allowance Recorded Investment",
        "terseLabel": "With related allowance, recorded investment"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance": {
     "auth_ref": [
      "r157"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.",
        "label": "Impaired Financing Receivable With Related Allowance Unpaid Principal Balance",
        "terseLabel": "With related allowance, unpaid principal balance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivablesTableTextBlock": {
     "auth_ref": [
      "r160"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of impaired financing receivables.",
        "label": "Impaired Financing Receivables Table [Text Block]",
        "terseLabel": "Impaired Loans"
       }
      }
     },
     "localname": "ImpairedFinancingReceivablesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_IncomeLossFromContinuingOperations": {
     "auth_ref": [
      "r79",
      "r101",
      "r128",
      "r344"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10070.0,
       "parentTag": "us-gaap_NetIncomeLoss",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax of income (loss) from continuing operations attributable to the parent.",
        "label": "Income Loss From Continuing Operations",
        "totalLabel": "(Loss) income from continuing operations"
       }
      }
     },
     "localname": "IncomeLossFromContinuingOperations",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest": {
     "auth_ref": [
      "r76",
      "r119",
      "r447",
      "r471",
      "r525"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10090.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperations",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.",
        "label": "Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest",
        "totalLabel": "(Loss) income from continuing operations before (benefit) provision for income taxes"
       }
      }
     },
     "localname": "IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeLossFromContinuingOperationsPerBasicShare": {
     "auth_ref": [
      "r74",
      "r78",
      "r124",
      "r126",
      "r127",
      "r468",
      "r472",
      "r474",
      "r521"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10030.0,
       "parentTag": "us-gaap_EarningsPerShareBasic",
       "weight": 1.0
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of net income (loss) from continuing operations per each share of common stock or unit outstanding during the reporting period.",
        "label": "Income Loss From Continuing Operations Per Basic Share",
        "terseLabel": "(Loss) income from continuing operations"
       }
      }
     },
     "localname": "IncomeLossFromContinuingOperationsPerBasicShare",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare": {
     "auth_ref": [
      "r74",
      "r78",
      "r124",
      "r126",
      "r127",
      "r128",
      "r474",
      "r521",
      "r523"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10010.0,
       "parentTag": "us-gaap_EarningsPerShareDiluted",
       "weight": 1.0
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of net income (loss) derived from continuing operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.",
        "label": "Income Loss From Continuing Operations Per Diluted Share",
        "terseLabel": "(Loss) income from continuing operations"
       }
      }
     },
     "localname": "IncomeLossFromContinuingOperationsPerDilutedShare",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Income Loss From Discontinued Operations Net Of Tax [Abstract]",
        "terseLabel": "Discontinued operations"
       }
      }
     },
     "localname": "IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity": {
     "auth_ref": [
      "r4",
      "r5",
      "r6",
      "r7",
      "r8",
      "r11",
      "r14",
      "r345"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10080.0,
       "parentTag": "us-gaap_NetIncomeLoss",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax of income (loss) from a discontinued operation attributable to the parent. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.",
        "label": "Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity",
        "negatedLabel": "Loss from discontinued operations",
        "terseLabel": "Loss from discontinued operations, net of taxes"
       }
      }
     },
     "localname": "IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeStatementAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Income Statement [Abstract]"
       }
      }
     },
     "localname": "IncomeStatementAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeStatementLocationAxis": {
     "auth_ref": [
      "r272"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by location in the income statement.",
        "label": "Income Statement Location [Axis]",
        "terseLabel": "Income Statement Location"
       }
      }
     },
     "localname": "IncomeStatementLocationAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeStatementLocationDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Location in the income statement.",
        "label": "Income Statement Location [Domain]",
        "terseLabel": "Income Statement Location"
       }
      }
     },
     "localname": "IncomeStatementLocationDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_IncomeTaxDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Income Tax Disclosure [Abstract]"
       }
      }
     },
     "localname": "IncomeTaxDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeTaxDisclosureTextBlock": {
     "auth_ref": [
      "r325"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.",
        "label": "Income Tax Disclosure [Text Block]",
        "terseLabel": "INCOME TAXES"
       }
      }
     },
     "localname": "IncomeTaxDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureIncomeTaxes"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_IncomeTaxExpenseBenefit": {
     "auth_ref": [
      "r110",
      "r136",
      "r323"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10100.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperations",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.",
        "label": "Income Tax Expense Benefit",
        "terseLabel": "(Benefit) provision for income taxes"
       }
      }
     },
     "localname": "IncomeTaxExpenseBenefit",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeTaxesPaidNet": {
     "auth_ref": [
      "r104"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.",
        "label": "Income Taxes Paid Net",
        "terseLabel": "Federal, foreign, state and local income taxes refunded, net"
       }
      }
     },
     "localname": "IncomeTaxesPaidNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInDeposits": {
     "auth_ref": [
      "r103",
      "r485"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10070.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The net cash inflow or outflow for the increase (decrease) in the beginning and end of period deposits balances.",
        "label": "Increase Decrease In Deposits",
        "terseLabel": "Net increase in deposits"
       }
      }
     },
     "localname": "IncreaseDecreaseInDeposits",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInLoansHeldForSale": {
     "auth_ref": [
      "r94",
      "r99"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10270.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The increase (decrease) during the reporting period in the value of loans or securitized loans that are held with the intention to sell in the near future.",
        "label": "Increase Decrease In Loans Held For Sale",
        "negatedLabel": "(Increase) decrease in loans held for sale"
       }
      }
     },
     "localname": "IncreaseDecreaseInLoansHeldForSale",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInOtherOperatingAssets": {
     "auth_ref": [
      "r99"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10290.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase (decrease) in operating assets classified as other.",
        "label": "Increase Decrease In Other Operating Assets",
        "negatedLabel": "Increase in other assets"
       }
      }
     },
     "localname": "IncreaseDecreaseInOtherOperatingAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInOtherOperatingLiabilities": {
     "auth_ref": [
      "r99"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10300.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase (decrease) in operating liabilities classified as other.",
        "label": "Increase Decrease In Other Operating Liabilities",
        "terseLabel": "Decrease in other liabilities"
       }
      }
     },
     "localname": "IncreaseDecreaseInOtherOperatingLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInStockholdersEquityRollForward": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.",
        "label": "Increase Decrease In Stockholders Equity Roll Forward",
        "terseLabel": "Increase (Decrease) in Stockholders' Equity [Roll Forward]"
       }
      }
     },
     "localname": "IncreaseDecreaseInStockholdersEquityRollForward",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_InterestAndDividendIncomeOperating": {
     "auth_ref": [
      "r476"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": 1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10240.0,
       "parentTag": "us-gaap_InterestIncomeExpenseNet",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.",
        "label": "Interest And Dividend Income Operating",
        "positiveLabel": "Interest income",
        "terseLabel": "Interest income",
        "totalLabel": "Interest income"
       }
      }
     },
     "localname": "InterestAndDividendIncomeOperating",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestAndDividendIncomeSecurities": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfInterestAndDividendIncomeDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10290.0,
       "parentTag": "us-gaap_InterestAndDividendIncomeOperating",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of operating dividend and interest income, including amortization and accretion of premiums and discounts, on securities.",
        "label": "Interest And Dividend Income Securities",
        "terseLabel": "Other interest and dividends",
        "totalLabel": "Total interest and dividends"
       }
      }
     },
     "localname": "InterestAndDividendIncomeSecurities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfInterestAndDividendIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestAndFeeIncomeLoansAndLeases": {
     "auth_ref": [
      "r475"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10280.0,
       "parentTag": "us-gaap_InterestAndDividendIncomeOperating",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The aggregate interest and fee income generated by: (1) loans the Entity has positive intent and ability to hold for the foreseeable future, or until maturity or payoff, including commercial and consumer loans, whether domestic or foreign, which may consist of: (a) industrial and agricultural; (b) real estate; and (c) real estate construction loans; (d) trade financing; (e) lease financing; (f) home equity lines-of-credit; (g) automobile and other vehicle loans; and (h) credit card and other revolving-type loans and (2) loans and leases held-for-sale which may include mortgage loans, direct financing, and sales-type leases.",
        "label": "Interest And Fee Income Loans And Leases",
        "terseLabel": "Interest and fees on loans"
       }
      }
     },
     "localname": "InterestAndFeeIncomeLoansAndLeases",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestBearingDepositLiabilities": {
     "auth_ref": [
      "r461"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfDetailOnDepositTypesDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_Deposits",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The aggregate of all domestic and foreign interest-bearing deposit liabilities.",
        "label": "Interest Bearing Deposit Liabilities",
        "terseLabel": "Interest-bearing"
       }
      }
     },
     "localname": "InterestBearingDepositLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfDetailOnDepositTypesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestBearingDepositsInBanks": {
     "auth_ref": [
      "r449",
      "r466"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10150.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnauditedParenthetical": {
       "order": 10020.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.",
        "label": "Interest Bearing Deposits In Banks",
        "positiveTerseLabel": "Interest-bearing cash, including restricted balances of $2.1 and $2.3 at March 31, 2020 and 2019, respectively",
        "terseLabel": "Interest bearing cash, including restricted balances of $2.1 at March 31, 2020 and $2.2 at December 31, 2019 (see Note 9 for amounts pledged)",
        "verboseLabel": "Cash and interest bearing deposits"
       }
      }
     },
     "localname": "InterestBearingDepositsInBanks",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnauditedParenthetical"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestExpense": {
     "auth_ref": [
      "r75",
      "r135",
      "r415",
      "r418",
      "r484"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10250.0,
       "parentTag": "us-gaap_InterestIncomeExpenseNet",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of the cost of borrowed funds accounted for as interest expense.",
        "label": "Interest Expense",
        "totalLabel": "Interest expense"
       }
      }
     },
     "localname": "InterestExpense",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestExpenseAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Interest Expense [Abstract]",
        "terseLabel": "Interest expense"
       }
      }
     },
     "localname": "InterestExpenseAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_InterestExpenseDeposits": {
     "auth_ref": [
      "r482"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10260.0,
       "parentTag": "us-gaap_InterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate amount of interest expense on all deposits.",
        "label": "Interest Expense Deposits",
        "terseLabel": "Interest on deposits"
       }
      }
     },
     "localname": "InterestExpenseDeposits",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestExpenseLongTermDebt": {
     "auth_ref": [
      "r483"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10270.0,
       "parentTag": "us-gaap_InterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate amount of interest paid or due on all long-term debt.",
        "label": "Interest Expense Long Term Debt",
        "terseLabel": "Interest on borrowings"
       }
      }
     },
     "localname": "InterestExpenseLongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestExpenseMember": {
     "auth_ref": [
      "r381"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Primary financial statement caption encompassing interest expense.",
        "label": "Interest Expense [Member]",
        "terseLabel": "Interest Expense"
       }
      }
     },
     "localname": "InterestExpenseMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InterestIncomeDebtSecuritiesAvailableForSaleOperating": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfInterestAndDividendIncomeDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_InterestAndDividendIncomeSecurities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of interest income, amortization of premium and accretion of discount on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale); classified as operating.",
        "label": "Interest Income Debt Securities Available For Sale Operating",
        "terseLabel": "Interest income - debt securities"
       }
      }
     },
     "localname": "InterestIncomeDebtSecuritiesAvailableForSaleOperating",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfInterestAndDividendIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss": {
     "auth_ref": [
      "r479"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10180.0,
       "parentTag": "us-gaap_RevenuesNetOfInterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of interest income or expense, including any amortization and accretion (as applicable) of discounts and premiums, including consideration of the provisions for loan, lease, credit, and other related losses.",
        "label": "Interest Income Expense After Provision For Loan Loss",
        "totalLabel": "Net interest revenue, after credit provision"
       }
      }
     },
     "localname": "InterestIncomeExpenseAfterProvisionForLoanLoss",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestIncomeExpenseNet": {
     "auth_ref": [
      "r477"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10220.0,
       "parentTag": "us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The net amount of operating interest income (expense).",
        "label": "Interest Income Expense Net",
        "totalLabel": "Net interest revenue"
       }
      }
     },
     "localname": "InterestIncomeExpenseNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestIncomeExpenseNetAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Interest Income Expense Net [Abstract]",
        "terseLabel": "Interest income"
       }
      }
     },
     "localname": "InterestIncomeExpenseNetAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_InterestPaidNet": {
     "auth_ref": [
      "r93",
      "r97",
      "r104"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash paid for interest, excluding capitalized interest, classified as operating activity. Includes, but is not limited to, payment to settle zero-coupon bond for accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount.",
        "label": "Interest Paid Net",
        "negatedLabel": "Interest paid"
       }
      }
     },
     "localname": "InterestPaidNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestRateContractMember": {
     "auth_ref": [
      "r311",
      "r378"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative instrument whose primary underlying risk is tied to the right to receive or pay a sum of money at a given interest rate.",
        "label": "Interest Rate Contract [Member]",
        "terseLabel": "Interest rate contracts"
       }
      }
     },
     "localname": "InterestRateContractMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InterestReceivable": {
     "auth_ref": [
      "r40"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.",
        "label": "Interest Receivable",
        "terseLabel": "Accrued interest receivable"
       }
      }
     },
     "localname": "InterestReceivable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InternalCreditAssessmentAxis": {
     "auth_ref": [
      "r162",
      "r228",
      "r237",
      "r239",
      "r292",
      "r386"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by entity-defined rating.",
        "label": "Internal Credit Assessment [Axis]",
        "terseLabel": "Internal Credit Assessment"
       }
      }
     },
     "localname": "InternalCreditAssessmentAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_InternalCreditAssessmentDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Entity defined credit risk rating.",
        "label": "Internal Credit Assessment [Domain]",
        "terseLabel": "Internal Credit Assessment"
       }
      }
     },
     "localname": "InternalCreditAssessmentDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InvestmentIncomeTextBlock": {
     "auth_ref": [
      "r81",
      "r82",
      "r83",
      "r526"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of investment income, including, but not limited to, interest and dividend income and amortization of discount (premium) derived from debt and equity securities. Excludes realized and unrealized gain (loss) on investments.",
        "label": "Investment Income [Text Block]",
        "terseLabel": "Schedule of Interest and Dividend Income"
       }
      }
     },
     "localname": "InvestmentIncomeTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_InvestmentPolicyTextBlock": {
     "auth_ref": [
      "r203"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy for investment in financial asset.",
        "label": "Investment Policy [Text Block]",
        "terseLabel": "Investments"
       }
      }
     },
     "localname": "InvestmentPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_InvestmentTableTextBlock": {
     "auth_ref": [
      "r198",
      "r201",
      "r204",
      "r205"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of investment.",
        "label": "Investment Table [Text Block]",
        "terseLabel": "Schedule of Carrying Value of Investment Securities"
       }
      }
     },
     "localname": "InvestmentTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_InvestmentTypeAxis": {
     "auth_ref": [
      "r529",
      "r530",
      "r531",
      "r532"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of investments.",
        "label": "Investment Type [Axis]",
        "terseLabel": "Investment Type"
       }
      }
     },
     "localname": "InvestmentTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_InvestmentTypeCategorizationMember": {
     "auth_ref": [
      "r529",
      "r530",
      "r531",
      "r532"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Asset obtained to generate income or appreciate in value.",
        "label": "Investment Type Categorization [Member]",
        "terseLabel": "Investments"
       }
      }
     },
     "localname": "InvestmentTypeCategorizationMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_Investments": {
     "auth_ref": [
      "r520"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10170.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sum of the carrying amounts as of the balance sheet date of all investments.",
        "label": "Investments",
        "positiveLabel": "Total investment securities",
        "verboseLabel": "Investment securities, including securities carried at fair value with changes recorded in net income of $0.0 at March 31, 2020 and $47.2 at December 31, 2019 (see Notes 6 and 9 for amounts pledged)"
       }
      }
     },
     "localname": "Investments",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfCarryingValueOfInvestmentSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InvestmentsClassifiedByContractualMaturityDateTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments.",
        "label": "Investments Classified By Contractual Maturity Date Table [Text Block]",
        "terseLabel": "Amortized Cost and Fair Value of Debt Securities by Contractual Maturity Dates"
       }
      }
     },
     "localname": "InvestmentsClassifiedByContractualMaturityDateTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Investments Debt And Equity Securities [Abstract]",
        "terseLabel": "AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"
       }
      }
     },
     "localname": "InvestmentsDebtAndEquitySecuritiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_InvestmentsFairValueDisclosure": {
     "auth_ref": [
      "r391"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.",
        "label": "Investments Fair Value Disclosure",
        "terseLabel": "Investment securities"
       }
      }
     },
     "localname": "InvestmentsFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock": {
     "auth_ref": [
      "r198",
      "r448",
      "r490",
      "r534"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for  investments in certain debt and equity securities.",
        "label": "Investments In Debt And Marketable Equity Securities And Certain Trading Assets Disclosure [Text Block]",
        "terseLabel": "INVESTMENT SECURITIES"
       }
      }
     },
     "localname": "InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecurities"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_JuniorLienMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Legal right, after the claims of senior lien holders are satisfied, for a creditor to possess property or other collateral in satisfaction of an outstanding debt in the event of borrower default or bankruptcy. Excludes second mortgage loans.",
        "label": "Junior Lien [Member]",
        "terseLabel": "Junior Lien Loans"
       }
      }
     },
     "localname": "JuniorLienMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LeasesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Leases [Abstract]"
       }
      }
     },
     "localname": "LeasesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend": {
     "auth_ref": [
      "r426"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Indicates (true false) whether lessee has option to extend operating lease.",
        "label": "Lessee Operating Lease Existence Of Option To Extend",
        "terseLabel": "Lessee, operating lease, option to extend"
       }
      }
     },
     "localname": "LesseeOperatingLeaseExistenceOfOptionToExtend",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesNarrativeDetails"
     ],
     "xbrltype": "booleanItemType"
    },
    "us-gaap_LesseeOperatingLeaseExistenceOfOptionToTerminate": {
     "auth_ref": [
      "r426"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Indicates (true false) whether lessee has option to terminate operating lease.",
        "label": "Lessee Operating Lease Existence Of Option To Terminate",
        "terseLabel": "Lessee, operating lease, option to terminate"
       }
      }
     },
     "localname": "LesseeOperatingLeaseExistenceOfOptionToTerminate",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesNarrativeDetails"
     ],
     "xbrltype": "booleanItemType"
    },
    "us-gaap_LesseeOperatingLeaseTermOfContract": {
     "auth_ref": [
      "r426"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.",
        "label": "Lessee Operating Lease Term Of Contract",
        "terseLabel": "Lessee, operating lease, remaining lease term"
       }
      }
     },
     "localname": "LesseeOperatingLeaseTermOfContract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_LetterOfCreditMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A document typically issued by a financial institution which acts as a guarantee of payment to a beneficiary, or as the source of payment for a specific transaction (for example, wiring funds to a foreign exporter if and when specified merchandise is accepted pursuant to the terms of the letter of credit).",
        "label": "Letter Of Credit [Member]",
        "terseLabel": "Letters of Credit"
       }
      }
     },
     "localname": "LetterOfCreditMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LeveragedLeasesIncomeStatementNetIncomeFromLeveragedLeases": {
     "auth_ref": [
      "r100",
      "r422",
      "r435"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails": {
       "order": 10040.0,
       "parentTag": "cit_LeaseIncomeIncludingIncomeOnLeverageLeases",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The total recognized during the period for income on leases meeting the criteria for classification as leveraged leases.",
        "label": "Leveraged Leases Income Statement Net Income From Leveraged Leases",
        "terseLabel": "Leveraged lease income"
       }
      }
     },
     "localname": "LeveragedLeasesIncomeStatementNetIncomeFromLeveragedLeases",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Liabilities": {
     "auth_ref": [
      "r34"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10010.0,
       "parentTag": "us-gaap_LiabilitiesAndStockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.",
        "label": "Liabilities",
        "totalLabel": "Total Liabilities"
       }
      }
     },
     "localname": "Liabilities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LiabilitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Liabilities [Abstract]",
        "terseLabel": "Liabilities"
       }
      }
     },
     "localname": "LiabilitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LiabilitiesAndStockholdersEquity": {
     "auth_ref": [
      "r30",
      "r454",
      "r519"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of liabilities and equity items, including the portion of equity attributable to noncontrolling interests, if any.",
        "label": "Liabilities And Stockholders Equity",
        "totalLabel": "Total Liabilities and Equity"
       }
      }
     },
     "localname": "LiabilitiesAndStockholdersEquity",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LiabilitiesFairValueDisclosure": {
     "auth_ref": [
      "r391"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of financial and nonfinancial obligations.",
        "label": "Liabilities Fair Value Disclosure",
        "negatedLabel": "Estimated fair value liabilities",
        "negatedTotalLabel": "Total Liabilities"
       }
      }
     },
     "localname": "LiabilitiesFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LienCategoryAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by category of lien, for example, but not limited to, senior or junior.",
        "label": "Lien Category [Axis]",
        "terseLabel": "Lien Category"
       }
      }
     },
     "localname": "LienCategoryAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LienCategoryDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Legal claim on the property of another party to secure the payment of a debt or the satisfaction of an obligation by category, for example, but not limited to, senior or junior.",
        "label": "Lien Category [Domain]",
        "terseLabel": "Lien Category"
       }
      }
     },
     "localname": "LienCategoryDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LineOfCredit": {
     "auth_ref": [
      "r20",
      "r452",
      "r511"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.",
        "label": "Line Of Credit",
        "terseLabel": "Outstanding borrowings"
       }
      }
     },
     "localname": "LineOfCredit",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LineOfCreditFacilityExpirationDate1": {
     "auth_ref": [
      "r32"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Date the credit facility terminates, in CCYY-MM-DD format.",
        "label": "Line Of Credit Facility Expiration Date1",
        "terseLabel": "Revolving credit facility, maturity date"
       }
      }
     },
     "localname": "LineOfCreditFacilityExpirationDate1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "dateItemType"
    },
    "us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity": {
     "auth_ref": [
      "r32"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.",
        "label": "Line Of Credit Facility Maximum Borrowing Capacity",
        "terseLabel": "Revolving credit facility, total commitment amount"
       }
      }
     },
     "localname": "LineOfCreditFacilityMaximumBorrowingCapacity",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LitigationSettlementAmountAwardedToOtherParty": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount awarded to other party in judgment or settlement of litigation.",
        "label": "Litigation Settlement Amount Awarded To Other Party",
        "terseLabel": "Litigation settlement amount"
       }
      }
     },
     "localname": "LitigationSettlementAmountAwardedToOtherParty",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureContingenciesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoanRestructuringTrialModificationsAmount": {
     "auth_ref": [
      "r164"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable modified on trial basis.",
        "label": "Loan Restructuring Trial Modifications Amount",
        "terseLabel": "Trial modification, amount"
       }
      }
     },
     "localname": "LoanRestructuringTrialModificationsAmount",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoanToValueAxis": {
     "auth_ref": [
      "r238"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by debt-to-value ratio, for example, but not limited to, 80% to 100%. Element name and standard label in Debt-to-Value [numeric lower end] to [numeric higher end] Percent [Member] or Debt-to-Value Greater Than [low end numeric value] Percent [Member] or Debt-to-Value Less Than [high end numeric value] Percent [Member] formats.",
        "label": "Loan To Value [Axis]",
        "terseLabel": "Debt-to-Value"
       }
      }
     },
     "localname": "LoanToValueAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LoanToValueDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt-to-value (DTV) ratio, for example, but not limited to, 80% to 100%. Element name and standard label in DTV [numeric lower end] to [numeric higher end] Percent [Member] or DTV Greater Than [low end numeric value] Percent [Member] or DTV Less Than [high end numeric value] Percent [Member] formats.",
        "label": "Loan To Value [Domain]",
        "terseLabel": "Debt-to-Value"
       }
      }
     },
     "localname": "LoanToValueDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LoansAndLeasesReceivableAllowanceForLoanLossesPolicy": {
     "auth_ref": [
      "r109",
      "r173"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy for estimating the allowance for losses on loans and lease receivables. The disclosure may include (a) how the entity determines each element of the allowance, (b) which loans are evaluated individually and which loans are evaluated as a group, (c) how the entity determines both the allocated and unallocated portions of the allowance, (d) how the entity determines the loss factors applied to graded loans in order to develop a general allowance, and (e) what self-correcting mechanism the entity uses to reduce differences between estimated and actual losses.",
        "label": "Loans And Leases Receivable Allowance For Loan Losses Policy",
        "terseLabel": "ASU 2016-13 Financial Instruments \u2013 Credit Losses (Topic 326)"
       }
      }
     },
     "localname": "LoansAndLeasesReceivableAllowanceForLoanLossesPolicy",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LoansAndLeasesReceivableDisclosureLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Loans And Leases Receivable Disclosure [Line Items]",
        "terseLabel": "Loans And Leases Receivable Disclosure [Line Items]"
       }
      }
     },
     "localname": "LoansAndLeasesReceivableDisclosureLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LoansAndLeasesReceivableDisclosureTable": {
     "auth_ref": [
      "r143"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about loans and leases receivable.",
        "label": "Loans And Leases Receivable Disclosure [Table]",
        "terseLabel": "Loans And Leases Receivable Disclosure [Table]"
       }
      }
     },
     "localname": "LoansAndLeasesReceivableDisclosureTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend": {
     "auth_ref": [
      "r180"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of unfunded portion of contractual agreement to lend funds to borrower for financing receivable modified as troubled debt restructuring.",
        "label": "Loans And Leases Receivable Impaired Commitment To Lend",
        "terseLabel": "Commitments to lend additional funds to borrowers whose loan terms have been modified in TDRs"
       }
      }
     },
     "localname": "LoansAndLeasesReceivableImpairedCommitmentToLend",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoansAndLeasesReceivableImpairedNonperformingAccrualOfInterest": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Reflects the carrying amount of loans deemed to be questionable as to collection on which interest is continuing to be earned or accrued.",
        "label": "Loans And Leases Receivable Impaired Nonperforming Accrual Of Interest",
        "terseLabel": "Accrued interest receivable on loans"
       }
      }
     },
     "localname": "LoansAndLeasesReceivableImpairedNonperformingAccrualOfInterest",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoansAndLeasesReceivablePastDueStatusPolicy": {
     "auth_ref": [
      "r109",
      "r168"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of the accounting policy for past due status of loans and leases receivable.",
        "label": "Loans And Leases Receivable Past Due Status Policy",
        "terseLabel": "Past Due and Non-Accrual Loans"
       }
      }
     },
     "localname": "LoansAndLeasesReceivablePastDueStatusPolicy",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LoansHeldForSaleMeasurementInput": {
     "auth_ref": [
      "r396"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value of input used to measure loan, held for sale.",
        "label": "Loans Held For Sale Measurement Input",
        "terseLabel": "Valuation input assumptions"
       }
      }
     },
     "localname": "LoansHeldForSaleMeasurementInput",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails"
     ],
     "xbrltype": "decimalItemType"
    },
    "us-gaap_LoansInsuredOrGuaranteedByGovernmentAuthoritiesAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by US and non-US government sponsored enterprise, authority, agency and program guarantees for government insured loans.",
        "label": "Loans Insured Or Guaranteed By Government Authorities [Axis]",
        "terseLabel": "Loans Insured or Guaranteed by Government Authorities"
       }
      }
     },
     "localname": "LoansInsuredOrGuaranteedByGovernmentAuthoritiesAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LoansInsuredOrGuaranteedByGovernmentAuthoritiesDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Guarantee by US and non-US government sponsored enterprises, authorities, agencies and programs for government insured loans.",
        "label": "Loans Insured Or Guaranteed By Government Authorities [Domain]",
        "terseLabel": "Loans Insured or Guaranteed by Government Authorities"
       }
      }
     },
     "localname": "LoansInsuredOrGuaranteedByGovernmentAuthoritiesDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LoansInsuredOrGuaranteedByUsGovernmentAuthoritiesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Guarantee by US government authority for government insured loans.",
        "label": "Loans Insured Or Guaranteed By Us Government Authorities [Member]",
        "terseLabel": "Loans Insured or Guaranteed by US Government Authorities"
       }
      }
     },
     "localname": "LoansInsuredOrGuaranteedByUsGovernmentAuthoritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock": {
     "auth_ref": [
      "r175"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.",
        "label": "Loans Notes Trade And Other Receivables Disclosure [Text Block]",
        "terseLabel": "LOANS"
       }
      }
     },
     "localname": "LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoans"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LoansReceivableFairValueDisclosure": {
     "auth_ref": [
      "r175"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.",
        "label": "Loans Receivable Fair Value Disclosure",
        "terseLabel": "Loans (excluding leases)"
       }
      }
     },
     "localname": "LoansReceivableFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoansReceivableMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "An amount of money or property, or a portion thereof, leant to a borrower (debtor) in exchange for a promise to repay the amount borrowed plus interest at a date certain in the future.",
        "label": "Loans Receivable [Member]",
        "terseLabel": "Commercial loans"
       }
      }
     },
     "localname": "LoansReceivableMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LondonInterbankOfferedRateLIBORMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Interest rate at which a bank borrows funds from other banks in the London interbank market.",
        "label": "London Interbank Offered Rate L I B O R [Member]",
        "terseLabel": "LIBOR"
       }
      }
     },
     "localname": "LondonInterbankOfferedRateLIBORMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LongTermDebt": {
     "auth_ref": [
      "r20",
      "r296",
      "r452",
      "r516"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10130.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.",
        "label": "Long Term Debt",
        "terseLabel": "Long-term borrowings",
        "verboseLabel": "Borrowings, including $514.0 at March 31, 2020 and $14.3 at December 31, 2019 contractually due within twelve months"
       }
      }
     },
     "localname": "LongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LongTermDebtFairValue": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.",
        "label": "Long Term Debt Fair Value",
        "terseLabel": "Long-term Debt"
       }
      }
     },
     "localname": "LongTermDebtFairValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths": {
     "auth_ref": [
      "r115",
      "r294"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Long Term Debt Maturities Repayments Of Principal In Next Twelve Months",
        "terseLabel": "Borrowings contractually due within twelve months"
       }
      }
     },
     "localname": "LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LongTermDebtTextBlock": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for long-term debt.",
        "label": "Long Term Debt [Text Block]",
        "terseLabel": "BORROWINGS"
       }
      }
     },
     "localname": "LongTermDebtTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowings"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LongtermDebtTypeAxis": {
     "auth_ref": [
      "r36"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of long-term debt.",
        "label": "Longterm Debt Type [Axis]",
        "terseLabel": "Long-term Debt, Type"
       }
      }
     },
     "localname": "LongtermDebtTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LongtermDebtTypeDomain": {
     "auth_ref": [
      "r36",
      "r295"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Type of long-term debt arrangement, such as notes, line of credit, commercial paper, asset-based financing, project financing, letter of credit financing. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the company, if longer.",
        "label": "Longterm Debt Type [Domain]",
        "terseLabel": "Long-term Debt, Type"
       }
      }
     },
     "localname": "LongtermDebtTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LongtermDebtWeightedAverageInterestRate": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Weighted average interest rate of long-term debt outstanding calculated at point in time.",
        "label": "Longterm Debt Weighted Average Interest Rate",
        "terseLabel": "Secured borrowings, weighted average percentage rate"
       }
      }
     },
     "localname": "LongtermDebtWeightedAverageInterestRate",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_LossContingenciesLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Loss Contingencies [Line Items]",
        "terseLabel": "Contingencies [Line Items]"
       }
      }
     },
     "localname": "LossContingenciesLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureContingenciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LossContingenciesTable": {
     "auth_ref": [
      "r279",
      "r280",
      "r281",
      "r283",
      "r284",
      "r285",
      "r286",
      "r290",
      "r291"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Discloses the specific components (such as the nature, name, and date) of the loss contingency and gives an estimate of the possible loss or range of loss, or states that a reasonable estimate cannot be made. Excludes environmental contingencies, warranties and unconditional purchase obligations.",
        "label": "Loss Contingencies [Table]",
        "terseLabel": "Loss Contingencies [Table]"
       }
      }
     },
     "localname": "LossContingenciesTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureContingenciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LossContingencyAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Loss Contingency [Abstract]"
       }
      }
     },
     "localname": "LossContingencyAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_LossContingencyDisclosures": {
     "auth_ref": [
      "r287",
      "r288"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for loss and gain contingencies. Describes any existing condition, situation, or set of circumstances involving uncertainty as of the balance sheet date (or prior to issuance of the financial statements) as to a probable or reasonably possible loss incurred by an entity that will ultimately be resolved when one or more future events occur or fail to occur, and typically discloses the amount of loss recorded or a range of possible loss, or an assertion that no reasonable estimate can be made.",
        "label": "Loss Contingency Disclosures",
        "terseLabel": "CONTINGENCIES"
       }
      }
     },
     "localname": "LossContingencyDisclosures",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureContingencies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LossContingencyNewClaimsFiledNumber": {
     "auth_ref": [
      "r282"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The total number of new claims filed pertaining to a loss contingency during the period.",
        "label": "Loss Contingency New Claims Filed Number",
        "terseLabel": "Individual lawsuits Filed"
       }
      }
     },
     "localname": "LossContingencyNewClaimsFiledNumber",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureContingenciesNarrativeDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "us-gaap_LossContingencyRangeOfPossibleLossPortionNotAccrued": {
     "auth_ref": [
      "r278"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The difference between the maximum amount of estimated loss and the amount recorded as of the balance sheet date.",
        "label": "Loss Contingency Range Of Possible Loss Portion Not Accrued",
        "terseLabel": "Amount of losses in excess of established reserves and insurance related to those matters"
       }
      }
     },
     "localname": "LossContingencyRangeOfPossibleLossPortionNotAccrued",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureContingenciesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Ltv80To100PercentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt-to-value (DTV) ratio from 80 to 100%. Element name and standard label in DTV [numeric lower end] to [numeric higher end] Percent [Member] format.",
        "label": "Ltv80 To100 Percent [Member]",
        "terseLabel": "LTV 80% \u2013 100%"
       }
      }
     },
     "localname": "Ltv80To100PercentMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LtvLessThan80PercentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt-to-value (DTV) ratio less than 80%. Element name and standard label in DTV Greater Than [low end numeric value] Percent [Member] or DTV Less Than [high end numeric value] Percent [Member] formats.",
        "label": "Ltv Less Than80 Percent [Member]",
        "terseLabel": "LTV Less than 80%"
       }
      }
     },
     "localname": "LtvLessThan80PercentMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MarginDepositAssets": {
     "auth_ref": [
      "r41"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of cash or securities placed with a broker or counterparty as security for a trading or derivatives securities position which was partially obtained with funds provided by the broker dealer.",
        "label": "Margin Deposit Assets",
        "terseLabel": "Variable margin balances, assets"
       }
      }
     },
     "localname": "MarginDepositAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_MaturityOfTimeDeposits": {
     "auth_ref": [
      "r545"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Period of time between issuance and maturity of customer deposits, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.",
        "label": "Maturity Of Time Deposits",
        "terseLabel": "Certificates of deposit, maturity term"
       }
      }
     },
     "localname": "MaturityOfTimeDeposits",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_MeasurementInputControlPremiumMember": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement input using amount above fair value that investor seeking to acquire control of entity will pay.",
        "label": "Measurement Input Control Premium [Member]",
        "terseLabel": "Control Premium"
       }
      }
     },
     "localname": "MeasurementInputControlPremiumMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MeasurementInputDefaultRateMember": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement input using likelihood loan will not be repaid as proportion of outstanding loan.",
        "label": "Measurement Input Default Rate [Member]",
        "terseLabel": "Default Rate"
       }
      }
     },
     "localname": "MeasurementInputDefaultRateMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MeasurementInputDiscountRateMember": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement input using interest rate to determine present value of future cash flows.",
        "label": "Measurement Input Discount Rate [Member]",
        "terseLabel": "Discount Rate"
       }
      }
     },
     "localname": "MeasurementInputDiscountRateMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MeasurementInputLongTermRevenueGrowthRateMember": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement input using compounded annualized rate of long-term growth in revenue.",
        "label": "Measurement Input Long Term Revenue Growth Rate [Member]",
        "terseLabel": "Long-Term Revenue Growth Rate"
       }
      }
     },
     "localname": "MeasurementInputLongTermRevenueGrowthRateMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MeasurementInputLossSeverityMember": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement input using loss, including, but not limited to, interest and write-down of principal, incurred on defaulted security as proportion of principal balance.",
        "label": "Measurement Input Loss Severity [Member]",
        "terseLabel": "Severity Rate"
       }
      }
     },
     "localname": "MeasurementInputLossSeverityMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MeasurementInputPrepaymentRateMember": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement input using principal prepayment at other than constant rate as proportion of outstanding loan principal.",
        "label": "Measurement Input Prepayment Rate [Member]",
        "terseLabel": "Prepayment Rate"
       }
      }
     },
     "localname": "MeasurementInputPrepaymentRateMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MeasurementInputTypeAxis": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of measurement input used to determine value of asset and liability.",
        "label": "Measurement Input Type [Axis]",
        "terseLabel": "Measurement Input Type"
       }
      }
     },
     "localname": "MeasurementInputTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_MeasurementInputTypeDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement input used to determine value of asset and liability.",
        "label": "Measurement Input Type [Domain]",
        "terseLabel": "Measurement Input Type"
       }
      }
     },
     "localname": "MeasurementInputTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember": {
     "auth_ref": [
      "r311"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt securities collateralized by real estate mortgage loans (mortgages), issued by US Government Sponsored Enterprises, such as Federal Home Loan Mortgage Corporation (FHLMC or Freddie Mac).",
        "label": "Mortgage Backed Securities Issued By U S Government Sponsored Enterprises [Member]",
        "terseLabel": "Residential MBS \u2013 U.S. government/sponsored agency"
       }
      }
     },
     "localname": "MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MortgageLoansInProcessOfForeclosureAmount": {
     "auth_ref": [
      "r166"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.",
        "label": "Mortgage Loans In Process Of Foreclosure Amount",
        "terseLabel": "Loans in process of foreclosure"
       }
      }
     },
     "localname": "MortgageLoansInProcessOfForeclosureAmount",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansInProcessOfForeclosureDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansInProcessOfForeclosureParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_MortgageLoansOnRealEstateAmortizationOfPremium": {
     "auth_ref": [
      "r537"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of decrease in investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, from amortization of premium.",
        "label": "Mortgage Loans On Real Estate Amortization Of Premium",
        "terseLabel": "Loans with terms that permitted negative amortization, unpaid principal balance"
       }
      }
     },
     "localname": "MortgageLoansOnRealEstateAmortizationOfPremium",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInFinancingActivities": {
     "auth_ref": [
      "r96"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10030.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.",
        "label": "Net Cash Provided By Used In Financing Activities",
        "totalLabel": "Net cash flows provided by financing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInFinancingActivities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Net Cash Provided By Used In Financing Activities [Abstract]",
        "terseLabel": "Cash Flows from Financing Activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInFinancingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetCashProvidedByUsedInInvestingActivities": {
     "auth_ref": [
      "r96"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10020.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.",
        "label": "Net Cash Provided By Used In Investing Activities",
        "totalLabel": "Net cash flows provided by (used in) investing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInInvestingActivities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Net Cash Provided By Used In Investing Activities [Abstract]",
        "terseLabel": "Cash Flows from Investing Activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInInvestingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetCashProvidedByUsedInOperatingActivities": {
     "auth_ref": [
      "r96",
      "r98",
      "r101"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10010.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
       "weight": 1.0
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.",
        "label": "Net Cash Provided By Used In Operating Activities",
        "totalLabel": "Net cash flows (used in) provided by operations"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInOperatingActivities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Net Cash Provided By Used In Operating Activities [Abstract]",
        "terseLabel": "Cash Flows from Operations"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInOperatingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetIncomeLoss": {
     "auth_ref": [
      "r66",
      "r69",
      "r77",
      "r101",
      "r129",
      "r473",
      "r522"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10200.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited": {
       "order": 10010.0,
       "parentTag": "us-gaap_ComprehensiveIncomeNetOfTax",
       "weight": 1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10050.0,
       "parentTag": "us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.",
        "label": "Net Income Loss",
        "negatedLabel": "Net loss",
        "positiveVerboseLabel": "Net (loss) income",
        "terseLabel": "Net (loss) income",
        "totalLabel": "Net (loss) income"
       }
      }
     },
     "localname": "NetIncomeLoss",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic": {
     "auth_ref": [
      "r119",
      "r122"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.",
        "label": "Net Income Loss Available To Common Stockholders Basic",
        "totalLabel": "Net (loss) income available to common shareholders"
       }
      }
     },
     "localname": "NetIncomeLossAvailableToCommonStockholdersBasic",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic": {
     "auth_ref": [
      "r122",
      "r125",
      "r128"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) from continuing operations available to common shareholders.",
        "label": "Net Income Loss From Continuing Operations Available To Common Shareholders Basic",
        "terseLabel": "(Loss) income from continuing operations available to common shareholders"
       }
      }
     },
     "localname": "NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetInvestmentHedgingMember": {
     "auth_ref": [
      "r366"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Hedges of a net investment in a foreign operation.",
        "label": "Net Investment Hedging [Member]",
        "terseLabel": "Net Investment Hedges"
       }
      }
     },
     "localname": "NetInvestmentHedgingMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsPreTaxNetGainsLossesRelatingToDerivativesDesignatedAsNetInvestmentHedgesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1": {
     "auth_ref": [
      "r117",
      "r120"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.",
        "label": "New Accounting Pronouncement Or Change In Accounting Principle Cumulative Effect Of Change On Equity Or Net Assets1",
        "negatedLabel": "Cumulative effect adjustment, decrease in retained earnings"
       }
      }
     },
     "localname": "NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.",
        "label": "New Accounting Pronouncement Or Change In Accounting Principle Effect Of Adoption Quantification",
        "terseLabel": "Legacy CIT(1) CECL adoption"
       }
      }
     },
     "localname": "NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "New Accounting Pronouncements Or Change In Accounting Principle [Line Items]",
        "terseLabel": "New Accounting Pronouncements or Change in Accounting Principle [Line Items]"
       }
      }
     },
     "localname": "NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable": {
     "auth_ref": [
      "r118",
      "r120"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Summarization of the changes in an accounting principle or a new accounting pronouncement, including the line items affected by the change and the financial effects of the change on those particular line items.",
        "label": "New Accounting Pronouncements Or Change In Accounting Principle [Table]",
        "terseLabel": "New Accounting Pronouncements Or Change In Accounting Principle [Table]"
       }
      }
     },
     "localname": "NewAccountingPronouncementsOrChangeInAccountingPrincipleTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy pertaining to new accounting pronouncements that may impact the entity's financial reporting. Includes, but is not limited to, quantification of the expected or actual impact.",
        "label": "New Accounting Pronouncements Policy Policy [Text Block]",
        "terseLabel": "Recent Accounting Pronouncements"
       }
      }
     },
     "localname": "NewAccountingPronouncementsPolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_NondesignatedMember": {
     "auth_ref": [
      "r367"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative instrument not designated as hedging instrument under Generally Accepted Accounting Principles (GAAP).",
        "label": "Nondesignated [Member]",
        "terseLabel": "Derivatives not designated as hedging instruments (Non-qualifying Hedges)",
        "verboseLabel": "Non-Qualifying Hedges"
       }
      }
     },
     "localname": "NondesignatedMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfNonQualifyingHedgesRecognizedAsOtherNonInterestIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_NoninterestBearingDepositLiabilities": {
     "auth_ref": [
      "r461"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfDetailOnDepositTypesDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_Deposits",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The aggregate amount of all domestic and foreign noninterest-bearing deposits liabilities held by the entity.",
        "label": "Noninterest Bearing Deposit Liabilities",
        "terseLabel": "Non-interest bearing"
       }
      }
     },
     "localname": "NoninterestBearingDepositLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfDetailOnDepositTypesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NoninterestExpense": {
     "auth_ref": [
      "r481"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10120.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total aggregate amount of all noninterest expense.",
        "label": "Noninterest Expense",
        "totalLabel": "Total non-interest expenses"
       }
      }
     },
     "localname": "NoninterestExpense",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NoninterestExpenseAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Noninterest Expense [Abstract]",
        "terseLabel": "Non-interest expenses"
       }
      }
     },
     "localname": "NoninterestExpenseAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NoninterestIncome": {
     "auth_ref": [
      "r480"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10190.0,
       "parentTag": "us-gaap_RevenuesNetOfInterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified.",
        "label": "Noninterest Income",
        "positiveLabel": "Non-interest income",
        "totalLabel": "Total non-interest income"
       }
      }
     },
     "localname": "NoninterestIncome",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NoninterestIncomeAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Noninterest Income [Abstract]",
        "terseLabel": "Non-interest income"
       }
      }
     },
     "localname": "NoninterestIncomeAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NoninterestIncomeOtherOperatingIncome": {
     "auth_ref": [
      "r73",
      "r470",
      "r524"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails": {
       "order": 10050.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": 1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10210.0,
       "parentTag": "us-gaap_NoninterestIncome",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of revenue earned, classified as other, excluding interest income.",
        "label": "Noninterest Income Other Operating Income",
        "terseLabel": "Other non-interest income"
       }
      }
     },
     "localname": "NoninterestIncomeOtherOperatingIncome",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NotesReceivableNet": {
     "auth_ref": [
      "r25",
      "r143",
      "r227"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10190.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.",
        "label": "Notes Receivable Net",
        "totalLabel": "Total loans, net of allowance for credit losses"
       }
      }
     },
     "localname": "NotesReceivableNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NumberOfBusinessesAcquired": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The number of businesses acquired by the entity during the period.",
        "label": "Number Of Businesses Acquired",
        "terseLabel": "Number of bank branches acquired"
       }
      }
     },
     "localname": "NumberOfBusinessesAcquired",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "us-gaap_OffBalanceSheetCreditLossLiability": {
     "auth_ref": [
      "r208",
      "r289"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.",
        "label": "Off Balance Sheet Credit Loss Liability",
        "terseLabel": "Allowance for off-balance sheet, credit exposures"
       }
      }
     },
     "localname": "OffBalanceSheetCreditLossLiability",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesParentheticalDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingExpenseMember": {
     "auth_ref": [
      "r381"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Primary financial statement caption encompassing expenses associated with normal operations.",
        "label": "Operating Expense [Member]",
        "terseLabel": "Operating Expenses"
       }
      }
     },
     "localname": "OperatingExpenseMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OperatingLeaseLeaseIncome": {
     "auth_ref": [
      "r131",
      "r430",
      "r434"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails": {
       "order": 10010.0,
       "parentTag": "cit_LeaseIncomeIncludingIncomeOnLeverageLeases",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable.",
        "label": "Operating Lease Lease Income",
        "totalLabel": "Rental income on operating leases"
       }
      }
     },
     "localname": "OperatingLeaseLeaseIncome",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseLeaseIncomeLeasePayments": {
     "auth_ref": [
      "r131",
      "r432"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails": {
       "order": 10050.0,
       "parentTag": "us-gaap_OperatingLeaseLeaseIncome",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of operating lease income from lease payments paid and payable to lessor. Excludes variable lease payments not included in measurement of lease receivable.",
        "label": "Operating Lease Lease Income Lease Payments",
        "terseLabel": "Lease income \u2013 Operating leases"
       }
      }
     },
     "localname": "OperatingLeaseLeaseIncomeLeasePayments",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseLiability": {
     "auth_ref": [
      "r424"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Present value of lessee's discounted obligation for lease payments from operating lease.",
        "label": "Operating Lease Liability",
        "verboseLabel": "Lease liabilities"
       }
      }
     },
     "localname": "OperatingLeaseLiability",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfSupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeasePayments": {
     "auth_ref": [
      "r425",
      "r427"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.",
        "label": "Operating Lease Payments",
        "terseLabel": "Cash paid for amounts included in the measurement of lease liabilities"
       }
      }
     },
     "localname": "OperatingLeasePayments",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfSupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseRightOfUseAsset": {
     "auth_ref": [
      "r423"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's right to use underlying asset under operating lease.",
        "label": "Operating Lease Right Of Use Asset",
        "verboseLabel": "ROU assets"
       }
      }
     },
     "localname": "OperatingLeaseRightOfUseAsset",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfSupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseVariableLeaseIncome": {
     "auth_ref": [
      "r131",
      "r433"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails": {
       "order": 10060.0,
       "parentTag": "us-gaap_OperatingLeaseLeaseIncome",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of operating lease income from variable lease payments paid and payable to lessor, excluding amount included in measurement of lease receivable.",
        "label": "Operating Lease Variable Lease Income",
        "terseLabel": "Variable lease income \u2013 Operating leases"
       }
      }
     },
     "localname": "OperatingLeaseVariableLeaseIncome",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeasesIncomeStatementDepreciationExpenseOnPropertySubjectToOrHeldForLease": {
     "auth_ref": [
      "r271"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails": {
       "order": 10060.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": -1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10130.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The total depreciation charge recorded for property subject to or held for lease.",
        "label": "Operating Leases Income Statement Depreciation Expense On Property Subject To Or Held For Lease",
        "terseLabel": "Depreciation on operating lease equipment"
       }
      }
     },
     "localname": "OperatingLeasesIncomeStatementDepreciationExpenseOnPropertySubjectToOrHeldForLease",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeasesIncomeStatementLeaseRevenue": {
     "auth_ref": [
      "r420"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails": {
       "order": 10040.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": 1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10200.0,
       "parentTag": "us-gaap_NoninterestIncome",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The total amount of revenue recognized for the period from operating leases, including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue.",
        "label": "Operating Leases Income Statement Lease Revenue",
        "terseLabel": "Rental income on operating leases"
       }
      }
     },
     "localname": "OperatingLeasesIncomeStatementLeaseRevenue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingSegmentsMember": {
     "auth_ref": [
      "r134",
      "r140"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Identifies components of an entity that engage in business activities from which they may earn revenue and incur expenses, including transactions with other components of the same entity.",
        "label": "Operating Segments [Member]",
        "terseLabel": "Operating Segments"
       }
      }
     },
     "localname": "OperatingSegmentsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Organization Consolidation And Presentation Of Financial Statements [Abstract]"
       }
      }
     },
     "localname": "OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureAndSignificantAccountingPoliciesTextBlock": {
     "auth_ref": [
      "r16",
      "r116",
      "r132",
      "r361"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows.  Describes procedure if disclosures are provided in more than one note to the financial statements.",
        "label": "Organization Consolidation And Presentation Of Financial Statements Disclosure And Significant Accounting Policies [Text Block]",
        "terseLabel": "BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES"
       }
      }
     },
     "localname": "OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureAndSignificantAccountingPoliciesTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_OtherAssets": {
     "auth_ref": [
      "r18",
      "r450",
      "r514"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10230.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of assets classified as other.",
        "label": "Other Assets",
        "terseLabel": "Other assets, including $546.5 at March 31, 2020 and $190.7 at December 31, 2019, at fair value"
       }
      }
     },
     "localname": "OtherAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherAssetsFairValueDisclosure": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of other assets.",
        "label": "Other Assets Fair Value Disclosure",
        "terseLabel": "Other assets at fair value"
       }
      }
     },
     "localname": "OtherAssetsFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherAssetsMember": {
     "auth_ref": [
      "r368",
      "r388"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Primary financial statement caption encompassing other assets.",
        "label": "Other Assets [Member]",
        "terseLabel": "Other Assets"
       }
      }
     },
     "localname": "OtherAssetsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent": {
     "auth_ref": [
      "r59",
      "r61",
      "r345",
      "r348"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited": {
       "order": 10050.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for defined benefit plan, attributable to parent.",
        "label": "Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Portion Attributable To Parent",
        "negatedLabel": "Changes in benefit plans net gains and prior service (cost)/credit"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax": {
     "auth_ref": [
      "r64",
      "r72"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossNetOfTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax, before reclassification adjustments of other comprehensive income (loss).",
        "label": "Other Comprehensive Income Loss Before Reclassifications Net Of Tax",
        "terseLabel": "AOCI activity before reclassifications"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossBeforeTax": {
     "auth_ref": [
      "r202"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossNetOfTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before tax, after reclassification adjustments of other comprehensive income (loss).",
        "label": "Other Comprehensive Income Loss Before Tax",
        "terseLabel": "Gross Amount"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax": {
     "auth_ref": [
      "r52",
      "r414"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited": {
       "order": 10030.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.",
        "label": "Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax",
        "terseLabel": "Foreign currency translation adjustments"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossNetOfTax": {
     "auth_ref": [
      "r67",
      "r70",
      "r72",
      "r300"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax and reclassification adjustments of other comprehensive income (loss).",
        "label": "Other Comprehensive Income Loss Net Of Tax",
        "terseLabel": "Other comprehensive income, net of tax",
        "totalLabel": "Net current period AOCI"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract]"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent": {
     "auth_ref": [
      "r67",
      "r70",
      "r345",
      "r346",
      "r348"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited": {
       "order": 10020.0,
       "parentTag": "us-gaap_ComprehensiveIncomeNetOfTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax of other comprehensive income (loss) attributable to parent entity.",
        "label": "Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent",
        "totalLabel": "Other comprehensive income, net of tax"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossTax": {
     "auth_ref": [
      "r62",
      "r322",
      "r324"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossNetOfTax",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of tax expense (benefit) allocated to other comprehensive income (loss).",
        "label": "Other Comprehensive Income Loss Tax",
        "negatedLabel": "Tax"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax": {
     "auth_ref": [
      "r54",
      "r61"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited": {
       "order": 10040.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.",
        "label": "Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax",
        "terseLabel": "Net unrealized gains on available for sale securities"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherContractMember": {
     "auth_ref": [
      "r311",
      "r380"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Derivative instrument whose primary underlying risk is classified as other.",
        "label": "Other Contract [Member]",
        "terseLabel": "Other contracts"
       }
      }
     },
     "localname": "OtherContractMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsNotionalAmountAndFairValuesOfDerivativeFinancialInstrumentsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OtherIncomeMember": {
     "auth_ref": [
      "r384"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Primary financial statement caption encompassing other revenue.",
        "label": "Other Income [Member]",
        "terseLabel": "Other Non-interest income"
       }
      }
     },
     "localname": "OtherIncomeMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OtherIntangibleAssetsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Intangible assets classified as other.",
        "label": "Other Intangible Assets [Member]",
        "terseLabel": "Other"
       }
      }
     },
     "localname": "OtherIntangibleAssetsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OtherLiabilities": {
     "auth_ref": [
      "r464"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10120.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of liabilities classified as other.",
        "label": "Other Liabilities",
        "terseLabel": "Other liabilities, including $164.4 at March 31, 2020 and $100.8 at December 31, 2019, at fair value"
       }
      }
     },
     "localname": "OtherLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherLiabilitiesFairValueDisclosure": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of other liabilities.",
        "label": "Other Liabilities Fair Value Disclosure",
        "terseLabel": "Other liabilities at fair value"
       }
      }
     },
     "localname": "OtherLiabilitiesFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherOperatingActivitiesCashFlowStatement": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10310.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other cash or noncash adjustments to reconcile net income to cash provided by (used in) operating activities that are not separately disclosed in the statement of cash flows (for example,  cash received or cash paid during the current period for miscellaneous operating activities, net change during the reporting period in other assets or other liabilities).",
        "label": "Other Operating Activities Cash Flow Statement",
        "terseLabel": "Other operating activities"
       }
      }
     },
     "localname": "OtherOperatingActivitiesCashFlowStatement",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionInOtherComprehensiveIncomeLossBeforeTaxIncludingPortionAttributableToNoncontrollingInterest": {
     "auth_ref": [
      "r56",
      "r183"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before tax of other than temporary impairment (OTTI) loss on investments in available-for-sale and held-to-maturity debt securities, recognized in other comprehensive loss.",
        "label": "Other Than Temporary Impairment Losses Investments Portion In Other Comprehensive Income Loss Before Tax Including Portion Attributable To Noncontrolling Interest",
        "terseLabel": "Other than temporary impairment losses"
       }
      }
     },
     "localname": "OtherThanTemporaryImpairmentLossesInvestmentsPortionInOtherComprehensiveIncomeLossBeforeTaxIncludingPortionAttributableToNoncontrollingInterest",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PassMember": {
     "auth_ref": [
      "r162",
      "r228"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A category of financing receivables not considered to be special mention, substandard, doubtful, and loss receivables.",
        "label": "Pass [Member]",
        "terseLabel": "Pass",
        "verboseLabel": "Non-Criticized Loans"
       }
      }
     },
     "localname": "PassMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PastDueFinancingReceivablesTableTextBlock": {
     "auth_ref": [
      "r171",
      "r172",
      "r217",
      "r240"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of aging analysis for financing receivable.",
        "label": "Past Due Financing Receivables Table [Text Block]",
        "terseLabel": "Loans - Delinquency Status"
       }
      }
     },
     "localname": "PastDueFinancingReceivablesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_PaymentsForProceedsFromLoansAndLeases": {
     "auth_ref": [
      "r114"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10110.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The net cash outflow or inflow for the increase (decrease) in the beginning and end of period of loan and lease balances which are not originated or purchased specifically for resale. Includes cash payments and proceeds associated with (a) loans held-for-investment, (b) leases held-for-investment, and (c) both.",
        "label": "Payments For Proceeds From Loans And Leases",
        "negatedLabel": "Changes in loans, net"
       }
      }
     },
     "localname": "PaymentsForProceedsFromLoansAndLeases",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsForProceedsFromOtherInvestingActivities": {
     "auth_ref": [
      "r84",
      "r87",
      "r114"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10190.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash (inflow) outflow from investing activities classified as other.",
        "label": "Payments For Proceeds From Other Investing Activities",
        "negatedLabel": "Other investing activities"
       }
      }
     },
     "localname": "PaymentsForProceedsFromOtherInvestingActivities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsForRepurchaseOfCommonStock": {
     "auth_ref": [
      "r90"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10080.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash outflow to reacquire common stock during the period.",
        "label": "Payments For Repurchase Of Common Stock",
        "negatedLabel": "Repurchase of common stock"
       }
      }
     },
     "localname": "PaymentsForRepurchaseOfCommonStock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsOfDividends": {
     "auth_ref": [
      "r90"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10090.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.",
        "label": "Payments Of Dividends",
        "negatedLabel": "Dividends paid"
       }
      }
     },
     "localname": "PaymentsOfDividends",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquireBusinessesGross": {
     "auth_ref": [
      "r85",
      "r340"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.",
        "label": "Payments To Acquire Businesses Gross",
        "verboseLabel": "Consideration paid in cash"
       }
      }
     },
     "localname": "PaymentsToAcquireBusinessesGross",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired": {
     "auth_ref": [
      "r85"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10180.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.",
        "label": "Payments To Acquire Businesses Net Of Cash Acquired",
        "negatedLabel": "Acquisition, net of cash received"
       }
      }
     },
     "localname": "PaymentsToAcquireBusinessesNetOfCashAcquired",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquireLifeInsurancePolicies": {
     "auth_ref": [
      "r87",
      "r95"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10170.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash outflow for payment of premium on corporate-owned life insurance policy, classified as investing activities. Includes, but is not limited to, bank-owned life insurance policy.",
        "label": "Payments To Acquire Life Insurance Policies",
        "negatedLabel": "Purchase of bank owned life insurance"
       }
      }
     },
     "localname": "PaymentsToAcquireLifeInsurancePolicies",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquireMachineryAndEquipment": {
     "auth_ref": [
      "r86"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10150.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash outflow for acquisition of machinery and equipment.",
        "label": "Payments To Acquire Machinery And Equipment",
        "negatedLabel": "Purchases of assets to be leased and other equipment"
       }
      }
     },
     "localname": "PaymentsToAcquireMachineryAndEquipment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PledgedAssetsNotSeparatelyReportedFinanceReceivables": {
     "auth_ref": [
      "r443"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The carrying amount, as of the date of the latest financial statement presented, of finance receivables which are owned but transferred to serve as collateral for the payment of the related debt obligation, primarily a secured borrowing or repurchase agreement, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.",
        "label": "Pledged Assets Not Separately Reported Finance Receivables",
        "terseLabel": "Pledged assets"
       }
      }
     },
     "localname": "PledgedAssetsNotSeparatelyReportedFinanceReceivables",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PledgedFinancialInstrumentsNotSeparatelyReportedLoansReceivablePledgedAsCollateral": {
     "auth_ref": [
      "r444"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The sum of the carrying amounts, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of related debt obligations, primarily secured borrowings and repurchase agreements, and for which the transferees are not permitted to sell or re-pledge them to an unrelated party.",
        "label": "Pledged Financial Instruments Not Separately Reported Loans Receivable Pledged As Collateral",
        "terseLabel": "Pledged assets, loans"
       }
      }
     },
     "localname": "PledgedFinancialInstrumentsNotSeparatelyReportedLoansReceivablePledgedAsCollateral",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged": {
     "auth_ref": [
      "r444"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.",
        "label": "Pledged Financial Instruments Not Separately Reported Securities Pledged",
        "terseLabel": "Pledged assets, investments"
       }
      }
     },
     "localname": "PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesPledged",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PortionAtFairValueFairValueDisclosureMember": {
     "auth_ref": [
      "r408"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measured at fair value for financial reporting purposes.",
        "label": "Portion At Fair Value Fair Value Disclosure [Member]",
        "terseLabel": "Fair Value Disclosure Item Amounts [Default]"
       }
      }
     },
     "localname": "PortionAtFairValueFairValueDisclosureMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsCarryingValueOfHedgedItemsAndAssociatedCumulativeHedgingAdjustmentRelatingForFairValueHedgesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PreferredStockDividendsIncomeStatementImpact": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10060.0,
       "parentTag": "us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of preferred stock dividends that is an adjustment to net income apportioned to common stockholders.",
        "label": "Preferred Stock Dividends Income Statement Impact",
        "terseLabel": "Preferred stock dividends"
       }
      }
     },
     "localname": "PreferredStockDividendsIncomeStatementImpact",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PreferredStockDividendsPerShareCashPaid": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate dividends paid during the period for each share of preferred stock outstanding.",
        "label": "Preferred Stock Dividends Per Share Cash Paid",
        "terseLabel": "Dividends paid per share"
       }
      }
     },
     "localname": "PreferredStockDividendsPerShareCashPaid",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_PreferredStockMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Preferred shares may provide a preferential dividend to the dividend on common stock and may take precedence over common stock in the event of a liquidation. Preferred shares typically represent an ownership interest in the company.",
        "label": "Preferred Stock [Member]",
        "terseLabel": "Preferred Stock"
       }
      }
     },
     "localname": "PreferredStockMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PreferredStockParOrStatedValuePerShare": {
     "auth_ref": [
      "r23"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.",
        "label": "Preferred Stock Par Or Stated Value Per Share",
        "terseLabel": "Preferred Stock, par value (in dollars per share)"
       }
      }
     },
     "localname": "PreferredStockParOrStatedValuePerShare",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_PreferredStockSharesAuthorized": {
     "auth_ref": [
      "r23"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.",
        "label": "Preferred Stock Shares Authorized",
        "terseLabel": "Preferred Stock, shares authorized (in shares)"
       }
      }
     },
     "localname": "PreferredStockSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockSharesIssued": {
     "auth_ref": [
      "r23"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.",
        "label": "Preferred Stock Shares Issued",
        "terseLabel": "Preferred Stock, shares issued (in shares)"
       }
      }
     },
     "localname": "PreferredStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockSharesOutstanding": {
     "auth_ref": [
      "r23"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.",
        "label": "Preferred Stock Shares Outstanding",
        "terseLabel": "Preferred Stock, shares outstanding (in shares)"
       }
      }
     },
     "localname": "PreferredStockSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockValue": {
     "auth_ref": [
      "r23"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10030.0,
       "parentTag": "us-gaap_StockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate par or stated value of issued nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable preferred shares, par value and other disclosure concepts are in another section within stockholders' equity.",
        "label": "Preferred Stock Value",
        "terseLabel": "Preferred Stock: $0.01 par value, 100,000,000 shares authorized, 8,325,000 shares issued and outstanding at March 31, 2020 and December 31, 2019"
       }
      }
     },
     "localname": "PreferredStockValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromIssuanceOfLongTermDebt": {
     "auth_ref": [
      "r88"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10050.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.",
        "label": "Proceeds From Issuance Of Long Term Debt",
        "terseLabel": "Proceeds from the issuance of term debt and FHLB advances"
       }
      }
     },
     "localname": "ProceedsFromIssuanceOfLongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromPaymentsForOtherFinancingActivities": {
     "auth_ref": [
      "r89",
      "r92",
      "r114"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10100.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash inflow (outflow) from financing activities classified as other.",
        "label": "Proceeds From Payments For Other Financing Activities",
        "terseLabel": "Other financing activities"
       }
      }
     },
     "localname": "ProceedsFromPaymentsForOtherFinancingActivities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans": {
     "auth_ref": [
      "r84"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10160.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash inflow from proceeds From Sales of Wholly Owned Real Estate and Real Estate Acquired in Settlement of Loans.",
        "label": "Proceeds From Sale Of Wholly Owned Real Estate And Real Estate Acquired In Settlement Of Loans",
        "terseLabel": "Proceeds from sale of OREO, net of repurchases"
       }
      }
     },
     "localname": "ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertySubjectToOrAvailableForOperatingLeaseNet": {
     "auth_ref": [
      "r421"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10200.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of property, by major property class, net of accumulated depreciation, subject to or available for lease as of the balance sheet date.",
        "label": "Property Subject To Or Available For Operating Lease Net",
        "terseLabel": "Operating lease equipment, net",
        "verboseLabel": "Operating lease equipment, net (see Note 9 for amounts pledged)"
       }
      }
     },
     "localname": "PropertySubjectToOrAvailableForOperatingLeaseNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProvisionForLoanAndLeaseLosses": {
     "auth_ref": [
      "r99",
      "r148",
      "r478"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of expense related to estimated loss from loan and lease transactions.",
        "label": "Provision For Loan And Lease Losses",
        "terseLabel": "Provision for credit losses"
       }
      }
     },
     "localname": "ProvisionForLoanAndLeaseLosses",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProvisionForLoanLossesExpensed": {
     "auth_ref": [
      "r211",
      "r458",
      "r469"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": -1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10210.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      },
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10230.0,
       "parentTag": "us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of credit loss expense (reversal of expense) for financing receivable.",
        "label": "Provision For Loan Losses Expensed",
        "terseLabel": "Provision for credit losses",
        "verboseLabel": "Provision for credit losses"
       }
      }
     },
     "localname": "ProvisionForLoanLossesExpensed",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PurchaseCommitmentExcludingLongtermCommitmentAxis": {
     "auth_ref": [
      "r21",
      "r453",
      "r517"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by arrangement, in which the entity has agreed to expend funds to procure goods or services from one or more suppliers.",
        "label": "Purchase Commitment Excluding Longterm Commitment [Axis]",
        "terseLabel": "Purchase Commitment, Excluding Long-term Commitment"
       }
      }
     },
     "localname": "PurchaseCommitmentExcludingLongtermCommitmentAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PurchaseCommitmentExcludingLongtermCommitmentDomain": {
     "auth_ref": [
      "r21",
      "r453",
      "r517"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This item is intended to be populated, by the entity, with Members identifying each purchase commitment about which information required or determined to be disclosed is being provided. If only one such commitment exists, this item may be used to capture such information; if multiple commitments exist, this item is the dimensional default, which will aggregate such information, as appropriate.",
        "label": "Purchase Commitment Excluding Longterm Commitment [Domain]",
        "terseLabel": "Purchase Commitment, Excluding Long-term Commitment"
       }
      }
     },
     "localname": "PurchaseCommitmentExcludingLongtermCommitmentDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PurchaseCommitmentExcludingLongtermCommitmentTable": {
     "auth_ref": [
      "r21",
      "r453",
      "r517"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Summarization of information required or determined to be disclosed about arrangements in which the entity has agreed to expend funds to procure goods or services from one or more suppliers. Such disclosure may include identification of the goods or services to be purchased, identity of the seller, pricing, effects on pricing for failing to reach minimum quantities required to be purchased (such as penalties), cancellation rights, and termination provisions.",
        "label": "Purchase Commitment Excluding Longterm Commitment [Table]",
        "terseLabel": "Purchase Commitment Excluding Longterm Commitment [Table]"
       }
      }
     },
     "localname": "PurchaseCommitmentExcludingLongtermCommitmentTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureCommitmentsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_RatioOfIndebtednessToNetCapital1": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Indebtedness divided by net capital.",
        "label": "Ratio Of Indebtedness To Net Capital1",
        "terseLabel": "Revolving credit facility, minimum guarantor asset coverage ratio"
       }
      }
     },
     "localname": "RatioOfIndebtednessToNetCapital1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "pureItemType"
    },
    "us-gaap_ReceivableTypeDomain": {
     "auth_ref": [
      "r39"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financing arrangement representing a contractual right to receive money either on demand or on fixed and determinable dates.",
        "label": "Receivable Type [Domain]",
        "terseLabel": "Receivable"
       }
      }
     },
     "localname": "ReceivableTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansByProductDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ReceivablesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Receivables [Abstract]"
       }
      }
     },
     "localname": "ReceivablesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax": {
     "auth_ref": [
      "r64",
      "r65",
      "r72"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossNetOfTax",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax of reclassification adjustments of other comprehensive income (loss).",
        "label": "Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax",
        "negatedLabel": "Amounts reclassified from AOCI"
       }
      }
     },
     "localname": "ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by item reclassified out of accumulated other comprehensive income (loss).",
        "label": "Reclassification Out Of Accumulated Other Comprehensive Income [Axis]",
        "terseLabel": "Reclassification out of Accumulated Other Comprehensive Income"
       }
      }
     },
     "localname": "ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Item reclassified out of accumulated other comprehensive income (loss).",
        "label": "Reclassification Out Of Accumulated Other Comprehensive Income [Domain]",
        "terseLabel": "Reclassification out of Accumulated Other Comprehensive Income"
       }
      }
     },
     "localname": "ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Identifies item reclassified out of accumulated other comprehensive income (loss).",
        "label": "Reclassification Out Of Accumulated Other Comprehensive Income [Member]",
        "terseLabel": "Reclassifications Out of AOCI"
       }
      }
     },
     "localname": "ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of information about items reclassified out of accumulated other comprehensive income (loss).",
        "label": "Reclassification Out Of Accumulated Other Comprehensive Income Table [Text Block]",
        "terseLabel": "Schedule of Pretax and After-tax Components of Other Comprehensive Income"
       }
      }
     },
     "localname": "ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock": {
     "auth_ref": [
      "r500",
      "r501",
      "r502",
      "r503",
      "r504",
      "r505",
      "r506",
      "r507",
      "r510"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for regulatory capital requirement for depository and lending institutions. Institutions include, but not are not limited to, finance company, insured depository institution, bank holding company, savings and loan association holding company, bank and savings institution not federally insured, mortgage company, foreign financial institution and credit union.",
        "label": "Regulatory Capital Requirements Under Banking Regulations [Text Block]",
        "terseLabel": "Regulatory Capital"
       }
      }
     },
     "localname": "RegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapital"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_RepaymentsOfLongTermDebt": {
     "auth_ref": [
      "r91"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10060.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.",
        "label": "Repayments Of Long Term Debt",
        "negatedLabel": "Repayments of term debt, FHLB advances, and net settlements"
       }
      }
     },
     "localname": "RepaymentsOfLongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ReportingUnitAxis": {
     "auth_ref": [
      "r255",
      "r256"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by reporting unit.",
        "label": "Reporting Unit [Axis]",
        "terseLabel": "Reporting Unit"
       }
      }
     },
     "localname": "ReportingUnitAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ReportingUnitDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Level of reporting at which goodwill is tested for impairment.",
        "label": "Reporting Unit [Domain]",
        "terseLabel": "Reporting Unit"
       }
      }
     },
     "localname": "ReportingUnitDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RetainedEarningsAccumulatedDeficit": {
     "auth_ref": [
      "r27",
      "r305",
      "r518"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10070.0,
       "parentTag": "cit_CommonStockholdersEquityAttributableToParent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cumulative amount of the reporting entity's undistributed earnings or deficit.",
        "label": "Retained Earnings Accumulated Deficit",
        "terseLabel": "Retained earnings"
       }
      }
     },
     "localname": "RetainedEarningsAccumulatedDeficit",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RetainedEarningsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cumulative amount of the reporting entity's undistributed earnings or deficit.",
        "label": "Retained Earnings [Member]",
        "terseLabel": "Retained Earnings"
       }
      }
     },
     "localname": "RetainedEarningsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RevenuesNetOfInterestExpense": {
     "auth_ref": [],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited": {
       "order": 10110.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income after deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).",
        "label": "Revenues Net Of Interest Expense",
        "totalLabel": "Total revenue, net of interest expense and credit provision"
       }
      }
     },
     "localname": "RevenuesNetOfInterestExpense",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RevolvingCreditFacilityMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Arrangement in which loan proceeds can continuously be obtained following repayments, but the total amount borrowed cannot exceed a specified maximum amount.",
        "label": "Revolving Credit Facility [Member]",
        "terseLabel": "Revolving Credit Facility"
       }
      }
     },
     "localname": "RevolvingCreditFacilityMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability": {
     "auth_ref": [
      "r428",
      "r429"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase in right-of-use asset obtained in exchange for operating lease liability.",
        "label": "Right Of Use Asset Obtained In Exchange For Operating Lease Liability",
        "terseLabel": "ROU assets obtained in exchange for new lease liabilities"
       }
      }
     },
     "localname": "RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfSupplementalBalanceSheetAndCashFlowInformationRelatedToLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_SalesTypeAndDirectFinancingLeasesInterestIncome": {
     "auth_ref": [
      "r431"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails": {
       "order": 10020.0,
       "parentTag": "cit_LeaseIncomeIncludingIncomeOnLeverageLeases",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of interest income from net investment in sales-type and direct financing leases.",
        "label": "Sales Type And Direct Financing Leases Interest Income",
        "terseLabel": "Interest income - Sales type and direct financing leases"
       }
      }
     },
     "localname": "SalesTypeAndDirectFinancingLeasesInterestIncome",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLeasesScheduleOfLeaseIncomeRelatedToCompanySOperatingAndFinanceLeasesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable": {
     "auth_ref": [
      "r39"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule itemizing specific types of trade accounts and notes receivable, and for each the gross carrying value, allowance, and net carrying value as of the balance sheet date. Presentation is categorized by current, noncurrent and unclassified receivables.",
        "label": "Schedule Of Accounts Notes Loans And Financing Receivable [Table]",
        "terseLabel": "Schedule Of Accounts Notes Loans And Financing Receivable [Table]"
       }
      }
     },
     "localname": "ScheduleOfAccountsNotesLoansAndFinancingReceivableTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfModificationsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfTdrsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock": {
     "auth_ref": [
      "r64"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the components of accumulated other comprehensive income (loss).",
        "label": "Schedule Of Accumulated Other Comprehensive Income Loss Table [Text Block]",
        "terseLabel": "Schedule of Accumulated Other Comprehensive Income (Loss)"
       }
      }
     },
     "localname": "ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock": {
     "auth_ref": [
      "r260"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the characteristics, including initial carrying value, residual amount, weighted average useful life, of finite-lived intangible assets acquired during the period by major class. A major class is composed of intangible assets that can be grouped together because they are similar, either by nature or by their use in the operations of the company.",
        "label": "Schedule Of Acquired Finite Lived Intangible Assets By Major Class [Text Block]",
        "terseLabel": "Summary of Intangible Assets"
       }
      }
     },
     "localname": "ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Schedule Of Available For Sale Securities [Line Items]",
        "terseLabel": "Schedule of Available-for-sale Securities [Line Items]"
       }
      }
     },
     "localname": "ScheduleOfAvailableForSaleSecuritiesLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable": {
     "auth_ref": [
      "r329",
      "r330"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule reflecting each material business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities.",
        "label": "Schedule Of Business Acquisitions By Acquisition [Table]",
        "terseLabel": "Schedule Of Business Acquisitions By Acquisition [Table]"
       }
      }
     },
     "localname": "ScheduleOfBusinessAcquisitionsByAcquisitionTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsConsiderationAndNetAssetsAcquiredDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSelectedUnauditedProFormaFinancialInformationDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfCommonStockOutstandingRollForwardTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the change in common stock outstanding.",
        "label": "Schedule Of Common Stock Outstanding Roll Forward Table [Text Block]",
        "terseLabel": "Schedule of Common Stock Activity"
       }
      }
     },
     "localname": "ScheduleOfCommonStockOutstandingRollForwardTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable": {
     "auth_ref": [
      "r499",
      "r502",
      "r507",
      "r509"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A table disclosing the capital amounts and ratios as of the balance sheet date indicating whether the entity or entities are in compliance with regulatory capital requirements, by entity.",
        "label": "Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Table]",
        "terseLabel": "Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Table]"
       }
      }
     },
     "localname": "ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock": {
     "auth_ref": [
      "r499",
      "r502",
      "r507",
      "r509"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the capital amounts and ratios as of the balance sheet date, indicating whether the entity or entities are in compliance with regulatory capital requirements, by entity.",
        "label": "Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Text Block]",
        "terseLabel": "Tier 1 Capital And Total Capital Components"
       }
      }
     },
     "localname": "ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfDebtInstrumentsTextBlock": {
     "auth_ref": [
      "r36",
      "r112",
      "r301",
      "r302",
      "r303",
      "r304",
      "r416",
      "r417",
      "r419",
      "r498"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.",
        "label": "Schedule Of Debt Instruments [Text Block]",
        "terseLabel": "Schedule of Long-Term Borrowings"
       }
      }
     },
     "localname": "ScheduleOfDebtInstrumentsTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock": {
     "auth_ref": [
      "r369",
      "r376",
      "r383"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the location and amount of derivative instruments and nonderivative instruments designated as hedging instruments reported before netting adjustments, and the amount of gain (loss) on derivative instruments and nonderivative instruments designated and qualified as hedging instruments.",
        "label": "Schedule Of Derivative Instruments Gain Loss In Statement Of Financial Performance [Text Block]",
        "terseLabel": "Derivative Instrument Gains and Losses on Non Qualifying Hedges Recognized as Other Non-interest Income"
       }
      }
     },
     "localname": "ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock": {
     "auth_ref": [
      "r391",
      "r392"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3).",
        "label": "Schedule Of Fair Value Assets And Liabilities Measured On Recurring Basis Table [Text Block]",
        "terseLabel": "Assets and Liabilities Measured at Fair Value on a Recurring Basis"
       }
      }
     },
     "localname": "ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfFairValueHedgingInstrumentsStatementsOfFinancialPerformanceAndFinancialPositionLocationTableTextBlock": {
     "auth_ref": [
      "r374"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure for fair value hedging instruments of (a) the location and amount of gains and losses reported in the statement of financial performance and (b) the location and fair value amounts of the instruments reported in the statement of financial position.",
        "label": "Schedule Of Fair Value Hedging Instruments Statements Of Financial Performance And Financial Position Location Table [Text Block]",
        "terseLabel": "Gains (Losses) of Fair Value Hedges Recognized as Interest Expense"
       }
      }
     },
     "localname": "ScheduleOfFairValueHedgingInstrumentsStatementsOfFinancialPerformanceAndFinancialPositionLocationTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfFederalHomeLoanBankAdvancesByBranchOfFHLBBankTextBlock": {
     "auth_ref": [
      "r463",
      "r493",
      "r498"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of advances by federal home loan bank by branch.",
        "label": "Schedule Of Federal Home Loan Bank Advances By Branch Of F H L B Bank [Text Block]",
        "terseLabel": "Schedule of FHLB Balances"
       }
      }
     },
     "localname": "ScheduleOfFederalHomeLoanBankAdvancesByBranchOfFHLBBankTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable": {
     "auth_ref": [
      "r216"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about allowance for credit loss on financing receivable.",
        "label": "Schedule Of Financing Receivable Allowance For Credit Losses [Table]",
        "terseLabel": "Schedule Of Financing Receivable Allowance For Credit Losses [Table]"
       }
      }
     },
     "localname": "ScheduleOfFinancingReceivableAllowanceForCreditLossesTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable": {
     "auth_ref": [
      "r228",
      "r239"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about credit quality indicator for financing receivable.",
        "label": "Schedule Of Financing Receivable Recorded Investment Credit Quality Indicator [Table]",
        "terseLabel": "Schedule Of Financing Receivable Recorded Investment Credit Quality Indicator [Table]"
       }
      }
     },
     "localname": "ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfFinancingReceivablesNonAccrualStatusTableTextBlock": {
     "auth_ref": [
      "r171",
      "r222"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of financing receivable on nonaccrual status.",
        "label": "Schedule Of Financing Receivables Non Accrual Status Table [Text Block]",
        "terseLabel": "Loans On Non-accrual Status"
       }
      }
     },
     "localname": "ScheduleOfFinancingReceivablesNonAccrualStatusTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfFinancingReceivablesPastDueTable": {
     "auth_ref": [
      "r217",
      "r240"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about aging analysis for financing receivable.",
        "label": "Schedule Of Financing Receivables Past Due [Table]",
        "terseLabel": "Schedule Of Financing Receivables Past Due [Table]"
       }
      }
     },
     "localname": "ScheduleOfFinancingReceivablesPastDueTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansDelinquencyStatusParentheticalDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable": {
     "auth_ref": [
      "r260",
      "r263"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.",
        "label": "Schedule Of Finite Lived Intangible Assets [Table]",
        "terseLabel": "Schedule Of Finite Lived Intangible Assets [Table]"
       }
      }
     },
     "localname": "ScheduleOfFiniteLivedIntangibleAssetsTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfGoodwillDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock": {
     "auth_ref": [
      "r260",
      "r263"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of assets, excluding financial assets and goodwill, lacking physical substance with a finite life, by either major class or business segment.",
        "label": "Schedule Of Finite Lived Intangible Assets Table [Text Block]",
        "terseLabel": "Summary of Intangible Assets Rollforward"
       }
      }
     },
     "localname": "ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfGoodwillTextBlock": {
     "auth_ref": [
      "r254",
      "r257"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of goodwill by reportable segment and in total which includes a rollforward schedule.",
        "label": "Schedule Of Goodwill [Text Block]",
        "terseLabel": "Summary of Goodwill"
       }
      }
     },
     "localname": "ScheduleOfGoodwillTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfImpairedFinancingReceivableTable": {
     "auth_ref": [
      "r160"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule of the recorded investment, unpaid principal balance, associated allowance, average recorded investment, accounting policies, and interest income recognized on the accrual and cash basis for impaired financing receivables by class of financing receivable.",
        "label": "Schedule Of Impaired Financing Receivable [Table]",
        "terseLabel": "Schedule Of Impaired Financing Receivable [Table]"
       }
      }
     },
     "localname": "ScheduleOfImpairedFinancingReceivableTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansImpairedLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCDLoansParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansPCILoansDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfNetInvestmentHedgesInAccumulatedOtherComprehensiveIncomeLossTableTextBlock": {
     "auth_ref": [
      "r377"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the effective portion of gains and losses on derivative instruments (and nonderivative instruments) designated and qualifying in net investment hedges recorded in accumulated other comprehensive income (loss) during the term of the hedging relationship and reclassified into earnings during the current period.",
        "label": "Schedule Of Net Investment Hedges In Accumulated Other Comprehensive Income Loss Table [Text Block]",
        "terseLabel": "Pre-tax Net Gains (Losses) Relating to Derivatives Designated as Net Investment Hedges"
       }
      }
     },
     "localname": "ScheduleOfNetInvestmentHedgesInAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfNotionalAmountsOfOutstandingDerivativePositionsTableTextBlock": {
     "auth_ref": [
      "r363"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the notional amounts of outstanding derivative positions.",
        "label": "Schedule Of Notional Amounts Of Outstanding Derivative Positions Table [Text Block]",
        "terseLabel": "Notional Amount and Fair Values of Derivative Financial Instruments"
       }
      }
     },
     "localname": "ScheduleOfNotionalAmountsOfOutstandingDerivativePositionsTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock": {
     "auth_ref": [
      "r334"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the amounts recognized as of the acquisition date for each major class of assets acquired and liabilities assumed. May include but not limited to the following: (a) acquired receivables; (b) contingencies recognized at the acquisition date; and (c) the fair value of noncontrolling interests in the acquiree.",
        "label": "Schedule Of Recognized Identified Assets Acquired And Liabilities Assumed Table [Text Block]",
        "terseLabel": "Consideration and Net Assets Acquired"
       }
      }
     },
     "localname": "ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable": {
     "auth_ref": [
      "r133",
      "r137",
      "r138",
      "r139",
      "r254"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A table disclosing the profit or loss and total assets for each reportable segment of the entity. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.",
        "label": "Schedule Of Segment Reporting Information By Segment [Table]",
        "terseLabel": "Schedule Of Segment Reporting Information By Segment [Table]"
       }
      }
     },
     "localname": "ScheduleOfSegmentReportingInformationBySegmentTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock": {
     "auth_ref": [
      "r133",
      "r137",
      "r138",
      "r139",
      "r254"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.",
        "label": "Schedule Of Segment Reporting Information By Segment [Text Block]",
        "terseLabel": "Segment Pre-Tax Income (Loss)"
       }
      }
     },
     "localname": "ScheduleOfSegmentReportingInformationBySegmentTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfVariableInterestEntitiesTable": {
     "auth_ref": [
      "r350",
      "r353",
      "r354",
      "r356",
      "r357"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of qualitative and quantitative information related to variable interests the entity holds, whether or not such variable interest entity (VIE) is included in the reporting entity's consolidated financial statements. Includes, but is not limited to, description of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a tabular comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide.",
        "label": "Schedule Of Variable Interest Entities [Table]",
        "terseLabel": "Schedule Of Variable Interest Entities [Table]"
       }
      }
     },
     "localname": "ScheduleOfVariableInterestEntitiesTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfVariableInterestEntitiesTextBlock": {
     "auth_ref": [
      "r350",
      "r353",
      "r354",
      "r356",
      "r357"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide.",
        "label": "Schedule Of Variable Interest Entities [Text Block]",
        "terseLabel": "Assets and Liabilities in Unconsolidated VIEs"
       }
      }
     },
     "localname": "ScheduleOfVariableInterestEntitiesTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SecuredDebt": {
     "auth_ref": [
      "r20",
      "r452",
      "r516"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.",
        "label": "Secured Debt",
        "verboseLabel": "Secured borrowings"
       }
      }
     },
     "localname": "SecuredDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_SecuritiesPurchasedUnderAgreementsToResell": {
     "auth_ref": [
      "r42",
      "r45",
      "r48",
      "r111",
      "r455"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10160.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after the effects of master netting arrangements, of funds outstanding loaned in the form of a security resale agreement between the entity and another party for the purchase and resale of identical or substantially the same securities at a date certain for a specified price. Includes purchases of participations in pools of securities that are subject to a resale agreement, assets not subject to a master netting arrangement and not elected to be offset.",
        "label": "Securities Purchased Under Agreements To Resell",
        "terseLabel": "Securities purchased under agreement to resell",
        "verboseLabel": "Securities purchased under agreements to resell outstanding"
       }
      }
     },
     "localname": "SecuritiesPurchasedUnderAgreementsToResell",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueCarryingAndEstimatedFairValuesOfFinancialInstrumentsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_SegmentDiscontinuedOperationsMember": {
     "auth_ref": [
      "r0",
      "r1",
      "r2",
      "r3"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Component or group of components disposed of or classified as held-for-sale and representing a strategic shift that has or will have a major effect on operations and financial results. Includes a business or nonprofit activity on acquisition classified as held-for-sale.",
        "label": "Segment Discontinued Operations [Member]",
        "terseLabel": "Discontinued Operations"
       }
      }
     },
     "localname": "SegmentDiscontinuedOperationsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SegmentDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Components of an entity that engage in business activities from which they may earn revenue and incur expenses, including transactions with other components of the same entity.",
        "label": "Segment [Domain]",
        "terseLabel": "Segments"
       }
      }
     },
     "localname": "SegmentDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfGoodwillDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SegmentReportingAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Segment Reporting [Abstract]"
       }
      }
     },
     "localname": "SegmentReportingAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_SegmentReportingDisclosureTextBlock": {
     "auth_ref": [
      "r142"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.",
        "label": "Segment Reporting Disclosure [Text Block]",
        "terseLabel": "BUSINESS SEGMENT INFORMATION"
       }
      }
     },
     "localname": "SegmentReportingDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformation"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SegmentReportingInformationAdditionalInformationAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Segment Reporting Information Additional Information [Abstract]",
        "terseLabel": "Select Period End Balances"
       }
      }
     },
     "localname": "SegmentReportingInformationAdditionalInformationAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SegmentReportingInformationLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Segment Reporting Information [Line Items]",
        "terseLabel": "Segment Reporting Information [Line Items]"
       }
      }
     },
     "localname": "SegmentReportingInformationLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SegmentReportingInformationProfitLossAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Segment Reporting Information Profit Loss [Abstract]",
        "terseLabel": "Segment Pre-tax Income (Loss)"
       }
      }
     },
     "localname": "SegmentReportingInformationProfitLossAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SeriesBPreferredStockMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Outstanding nonredeemable series B preferred stock or outstanding series B preferred stock. Classified within stockholders' equity if nonredeemable or redeemable solely at the option of the issuer. Classified within temporary equity if redemption is outside the control of the issuer.",
        "label": "Series B Preferred Stock [Member]",
        "terseLabel": "Series B Preferred Share"
       }
      }
     },
     "localname": "SeriesBPreferredStockMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ShareBasedCompensation": {
     "auth_ref": [
      "r99"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10230.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of noncash expense for share-based payment arrangement.",
        "label": "Share Based Compensation",
        "terseLabel": "Amortization of stock compensation expenses"
       }
      }
     },
     "localname": "ShareBasedCompensation",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of shares used to settle grantee's tax withholding obligation for award under share-based payment arrangement.",
        "label": "Shares Paid For Tax Withholding For Share Based Compensation",
        "negatedLabel": "Shares held to cover taxes on vesting restricted shares and other (in shares)"
       }
      }
     },
     "localname": "SharesPaidForTaxWithholdingForShareBasedCompensation",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShortTermDebtTypeAxis": {
     "auth_ref": [
      "r33"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of short-term debt arrangement.",
        "label": "Short Term Debt Type [Axis]",
        "terseLabel": "Short-term Debt, Type"
       }
      }
     },
     "localname": "ShortTermDebtTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ShortTermDebtTypeDomain": {
     "auth_ref": [
      "r31"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Type of short-term debt arrangement, such as notes, line of credit, commercial paper, asset-based financing, project financing, letter of credit financing.",
        "label": "Short Term Debt Type [Domain]",
        "terseLabel": "Short-term Debt, Type"
       }
      }
     },
     "localname": "ShortTermDebtTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SpecialMentionMember": {
     "auth_ref": [
      "r162",
      "r228"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A category of financing receivables considered to have potential weaknesses that deserve management's close attention. If left uncorrected, those potential weaknesses may result in a deterioration of the repayment prospects for the asset or of the creditor's position at some future date.",
        "label": "Special Mention [Member]",
        "terseLabel": "Special Mention"
       }
      }
     },
     "localname": "SpecialMentionMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_StatementBusinessSegmentsAxis": {
     "auth_ref": [
      "r9",
      "r137",
      "r254",
      "r273",
      "r274",
      "r275",
      "r527"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by business segments.",
        "label": "Statement Business Segments [Axis]",
        "terseLabel": "Segments"
       }
      }
     },
     "localname": "StatementBusinessSegmentsAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAllowanceForCreditLossesScheduleOfAllowanceForCreditLossesAndRecordedInvestmentInFinanceReceivablesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessSegmentInformationSegmentPreTaxIncomeLossDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfGoodwillDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansCommercialLoansByRiskRatingDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansCurrentFICOScoreDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfConsumerLoansLTVDistributionsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansScheduleOfLoansBySegmentBasedOnObligorLocationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementClassOfStockAxis": {
     "auth_ref": [
      "r22",
      "r23",
      "r24",
      "r300"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by the different classes of stock of the entity.",
        "label": "Statement Class Of Stock [Axis]",
        "terseLabel": "Class of Stock"
       }
      }
     },
     "localname": "StatementClassOfStockAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DocumentDocumentAndEntityInformation",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementEquityComponentsAxis": {
     "auth_ref": [
      "r38",
      "r300"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by component of equity.",
        "label": "Statement Equity Components [Axis]",
        "terseLabel": "Equity Components",
        "verboseLabel": "Unrealized net gains (losses) on AFS securities"
       }
      }
     },
     "localname": "StatementEquityComponentsAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityBeforeAndAfterTaxComponentsOfOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityComponentsOfAccumulatedOtherComprehensiveIncomeLossAOCIDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Statement [Line Items]",
        "terseLabel": "Statement [Line Items]"
       }
      }
     },
     "localname": "StatementLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfCashFlowsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statement Of Cash Flows [Abstract]"
       }
      }
     },
     "localname": "StatementOfCashFlowsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfFinancialPositionAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statement Of Financial Position [Abstract]"
       }
      }
     },
     "localname": "StatementOfFinancialPositionAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfStockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statement Of Stockholders Equity [Abstract]"
       }
      }
     },
     "localname": "StatementOfStockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule reflecting a Statement of Income, Statement of Cash Flows, Statement of Financial Position, Statement of Shareholders' Equity and Other Comprehensive Income, or other statement as needed.",
        "label": "Statement [Table]",
        "terseLabel": "Statement [Table]"
       }
      }
     },
     "localname": "StatementTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsTables",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockIssued1": {
     "auth_ref": [
      "r105",
      "r106",
      "r107"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The fair value of stock issued in noncash financing activities.",
        "label": "Stock Issued1",
        "terseLabel": "Issuance of common stock - acquisition"
       }
      }
     },
     "localname": "StockIssued1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesAcquisitions": {
     "auth_ref": [
      "r23",
      "r24",
      "r305"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of shares of stock issued during the period pursuant to acquisitions.",
        "label": "Stock Issued During Period Shares Acquisitions",
        "terseLabel": "Common stock issuance - acquisition"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesAcquisitions",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans": {
     "auth_ref": [
      "r23",
      "r24",
      "r300",
      "r305"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of shares issued during the period as a result of an employee stock purchase plan.",
        "label": "Stock Issued During Period Shares Employee Stock Purchase Plans",
        "terseLabel": "Employee stock purchase plan participation (in shares)"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures": {
     "auth_ref": [
      "r23",
      "r24",
      "r300",
      "r305"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of shares issued during the period related to Restricted Stock Awards, net of any shares forfeited.",
        "label": "Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures",
        "terseLabel": "Restricted stock issued (in shares)"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueAcquisitions": {
     "auth_ref": [
      "r38",
      "r300",
      "r305"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value of stock issued pursuant to acquisitions during the period.",
        "label": "Stock Issued During Period Value Acquisitions",
        "terseLabel": "Issuance of common stock - acquisition"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueAcquisitions",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan": {
     "auth_ref": [
      "r23",
      "r24",
      "r300",
      "r305"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate change in value for stock issued during the period as a result of employee stock purchase plan.",
        "label": "Stock Issued During Period Value Employee Stock Purchase Plan",
        "terseLabel": "Employee stock purchase plan"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueEmployeeStockPurchasePlan",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueNewIssues": {
     "auth_ref": [
      "r23",
      "r24",
      "r300",
      "r305"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.",
        "label": "Stock Issued During Period Value New Issues",
        "terseLabel": "Issuance of preferred stock"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueNewIssues",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation": {
     "auth_ref": [
      "r23",
      "r24",
      "r305",
      "r316",
      "r317"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value, after forfeiture, of shares issued under share-based payment arrangement. Excludes employee stock ownership plan (ESOP).",
        "label": "Stock Issued During Period Value Share Based Compensation",
        "terseLabel": "Amortization of stock compensation expenses"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueShareBasedCompensation",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockRepurchasedDuringPeriodValue": {
     "auth_ref": [
      "r23",
      "r24",
      "r300",
      "r305"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.",
        "label": "Stock Repurchased During Period Value",
        "negatedLabel": "Share repurchases"
       }
      }
     },
     "localname": "StockRepurchasedDuringPeriodValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquity": {
     "auth_ref": [
      "r24",
      "r28",
      "r29",
      "r174"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10020.0,
       "parentTag": "us-gaap_LiabilitiesAndStockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.",
        "label": "Stockholders Equity",
        "periodEndLabel": "Ending balance",
        "periodStartLabel": "Beginning balance",
        "totalLabel": "Total Equity"
       }
      }
     },
     "localname": "StockholdersEquity",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Stockholders Equity [Abstract]",
        "terseLabel": "Stockholders\u2019 Equity"
       }
      }
     },
     "localname": "StockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest": {
     "auth_ref": [
      "r342",
      "r343",
      "r358"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.",
        "label": "Stockholders Equity Including Portion Attributable To Noncontrolling Interest",
        "periodEndLabel": "Ending balance",
        "periodStartLabel": "Beginning balance"
       }
      }
     },
     "localname": "StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquityChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquityNoteAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Stockholders Equity Note [Abstract]"
       }
      }
     },
     "localname": "StockholdersEquityNoteAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockholdersEquityNoteDisclosureTextBlock": {
     "auth_ref": [
      "r310"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.",
        "label": "Stockholders Equity Note Disclosure [Text Block]",
        "terseLabel": "STOCKHOLDERS' EQUITY"
       }
      }
     },
     "localname": "StockholdersEquityNoteDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholdersEquity"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_StockholdersEquityOther": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This element represents movements included in the statement of changes in stockholders' equity which are not separately disclosed or provided for elsewhere in the taxonomy.",
        "label": "Stockholders Equity Other",
        "terseLabel": "Other"
       }
      }
     },
     "localname": "StockholdersEquityOther",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_SubordinatedDebtMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This element represents domestic or foreign subordinated debt. Subordinated debt has a lower priority of repayment in liquidation of the entity's assets.",
        "label": "Subordinated Debt [Member]",
        "terseLabel": "Subordinated debt"
       }
      }
     },
     "localname": "SubordinatedDebtMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SubsegmentsAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by business subsegments.",
        "label": "Subsegments [Axis]",
        "terseLabel": "Subsegments"
       }
      }
     },
     "localname": "SubsegmentsAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SubsegmentsDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Divisions of a component of an entity that engage in business activities from which they may earn revenue and incur expenses, including transactions with other components of the same entity.",
        "label": "Subsegments [Domain]",
        "terseLabel": "Subsegments"
       }
      }
     },
     "localname": "SubsegmentsDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfKeyValuationInputAssumptionsByDivisionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfLoanValuationsByDivisionInEachSegmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SupplementalCashFlowInformationAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Supplemental Cash Flow Information [Abstract]",
        "terseLabel": "Supplementary Cash Flow Disclosures"
       }
      }
     },
     "localname": "SupplementalCashFlowInformationAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_TangibleCapitalRequiredForCapitalAdequacyToTangibleAssets": {
     "auth_ref": [
      "r499",
      "r502",
      "r509"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The minimum amount of Tangible Capital divided by tangible assets (Tangible Capital Ratio) as defined in the regulations.",
        "label": "Tangible Capital Required For Capital Adequacy To Tangible Assets",
        "terseLabel": "Effective minimum ratios under Basel III guidelines"
       }
      }
     },
     "localname": "TangibleCapitalRequiredForCapitalAdequacyToTangibleAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_TangibleCapitalToTangibleAssets": {
     "auth_ref": [
      "r499",
      "r509"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tangible Capital divided by Tangible assets as defined in the regulations.",
        "label": "Tangible Capital To Tangible Assets",
        "terseLabel": "Actual"
       }
      }
     },
     "localname": "TangibleCapitalToTangibleAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_TierOneLeverageCapitalAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Tier One Leverage Capital [Abstract]",
        "terseLabel": "Tier 1 Leverage Ratio:"
       }
      }
     },
     "localname": "TierOneLeverageCapitalAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets": {
     "auth_ref": [
      "r499",
      "r502",
      "r509"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.",
        "label": "Tier One Leverage Capital Required For Capital Adequacy To Average Assets",
        "terseLabel": "Required minimum ratios under Basel III guidelines(1)"
       }
      }
     },
     "localname": "TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets": {
     "auth_ref": [
      "r499"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.",
        "label": "Tier One Leverage Capital Required To Be Well Capitalized To Average Assets",
        "terseLabel": "BHC and PCA Well-Capitalized"
       }
      }
     },
     "localname": "TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_TierOneLeverageCapitalToAverageAssets": {
     "auth_ref": [
      "r499",
      "r509"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tier 1 Leverage Capital divided by average assets as defined in the regulations.",
        "label": "Tier One Leverage Capital To Average Assets",
        "terseLabel": "Actual"
       }
      }
     },
     "localname": "TierOneLeverageCapitalToAverageAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_TierOneRiskBasedCapital": {
     "auth_ref": [
      "r499",
      "r509"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tier 1 Risk Based Capital as defined in the regulations.",
        "label": "Tier One Risk Based Capital",
        "terseLabel": "Tier 1 Capital"
       }
      }
     },
     "localname": "TierOneRiskBasedCapital",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TierOneRiskBasedCapitalAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Tier One Risk Based Capital [Abstract]",
        "terseLabel": "Tier 1 Capital Ratio:"
       }
      }
     },
     "localname": "TierOneRiskBasedCapitalAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets": {
     "auth_ref": [
      "r499",
      "r502",
      "r509"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.",
        "label": "Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets",
        "terseLabel": "Tier 1 Capital minimum ratio",
        "verboseLabel": "Effective minimum ratios under Basel III guidelines"
       }
      }
     },
     "localname": "TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets": {
     "auth_ref": [
      "r499"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as \"well capitalized\" under the regulatory framework for prompt corrective action.",
        "label": "Tier One Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets",
        "terseLabel": "BHC and PCA Well-Capitalized"
       }
      }
     },
     "localname": "TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets": {
     "auth_ref": [
      "r499",
      "r509"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tier 1 capital divided by risk weighted assets as defined by regulations.",
        "label": "Tier One Risk Based Capital To Risk Weighted Assets",
        "terseLabel": "Actual"
       }
      }
     },
     "localname": "TierOneRiskBasedCapitalToRiskWeightedAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalTier1CapitalAndTotalCapitalComponentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_TimeDepositMaturitiesAfterYearFive": {
     "auth_ref": [
      "r294"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails": {
       "order": 10060.0,
       "parentTag": "us-gaap_TimeDeposits",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposits maturing after the fifth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Time Deposit Maturities After Year Five",
        "terseLabel": "Over five years"
       }
      }
     },
     "localname": "TimeDepositMaturitiesAfterYearFive",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TimeDepositMaturitiesTableTextBlock": {
     "auth_ref": [
      "r294"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of time deposit liability maturities.",
        "label": "Time Deposit Maturities Table [Text Block]",
        "terseLabel": "Schedule of Maturities of Time Deposits"
       }
      }
     },
     "localname": "TimeDepositMaturitiesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_TimeDepositMaturitiesYearFive": {
     "auth_ref": [
      "r294"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails": {
       "order": 10050.0,
       "parentTag": "us-gaap_TimeDeposits",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposits maturing in the fifth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Time Deposit Maturities Year Five",
        "terseLabel": "Four to five years"
       }
      }
     },
     "localname": "TimeDepositMaturitiesYearFive",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TimeDepositMaturitiesYearFour": {
     "auth_ref": [
      "r294"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails": {
       "order": 10040.0,
       "parentTag": "us-gaap_TimeDeposits",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposits maturing in the fourth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Time Deposit Maturities Year Four",
        "terseLabel": "Three to four years"
       }
      }
     },
     "localname": "TimeDepositMaturitiesYearFour",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TimeDepositMaturitiesYearOne": {
     "auth_ref": [
      "r294"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails": {
       "order": 10010.0,
       "parentTag": "us-gaap_TimeDeposits",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposits maturing in the next fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Time Deposit Maturities Year One",
        "terseLabel": "Within one year"
       }
      }
     },
     "localname": "TimeDepositMaturitiesYearOne",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TimeDepositMaturitiesYearThree": {
     "auth_ref": [
      "r294"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails": {
       "order": 10030.0,
       "parentTag": "us-gaap_TimeDeposits",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposits maturing in the third fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Time Deposit Maturities Year Three",
        "terseLabel": "Two to three years"
       }
      }
     },
     "localname": "TimeDepositMaturitiesYearThree",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TimeDepositMaturitiesYearTwo": {
     "auth_ref": [
      "r294"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails": {
       "order": 10020.0,
       "parentTag": "us-gaap_TimeDeposits",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposits maturing in the second fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Time Deposit Maturities Year Two",
        "terseLabel": "One to two years"
       }
      }
     },
     "localname": "TimeDepositMaturitiesYearTwo",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TimeDeposits": {
     "auth_ref": [
      "r461",
      "r492"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposit liabilities, including certificates of deposit.",
        "label": "Time Deposits",
        "totalLabel": "Total Time deposits"
       }
      }
     },
     "localname": "TimeDeposits",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TimeDeposits100000OrMore": {
     "auth_ref": [
      "r545"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposit liabilities, including certificates of deposit, in denominations of $100,000 or more.",
        "label": "Time Deposits100000 Or More",
        "totalLabel": "Total"
       }
      }
     },
     "localname": "TimeDeposits100000OrMore",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfCertificatesOfDeposit100ThousandOrMoreDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit": {
     "auth_ref": [
      "r492"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of time deposit liabilities, including certificates of deposit, in denominations that meet or exceed the Federal Deposit Insurance Corporation (FDIC) insurance limit.",
        "label": "Time Deposits At Or Above F D I C Insurance Limit",
        "terseLabel": "Aggregate time deposits, $250,000 or more"
       }
      }
     },
     "localname": "TimeDepositsAtOrAboveFDICInsuranceLimit",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TimeDepositsByMaturityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Time Deposits By Maturity [Abstract]",
        "terseLabel": "Time deposits, remaining contractual maturity:"
       }
      }
     },
     "localname": "TimeDepositsByMaturityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDepositsScheduleOfMaturitiesOfTimeDepositsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_TradeNamesMember": {
     "auth_ref": [
      "r335"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Rights acquired through registration of a business name to gain or protect exclusive use thereof.",
        "label": "Trade Names [Member]",
        "terseLabel": "Trade Name",
        "verboseLabel": "Trade names"
       }
      }
     },
     "localname": "TradeNamesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureAcquisitionAndDiscontinuedOperationsSummaryOfIntangibleAssetsRecordedInConjunctionWithMOBTransactionDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsRollforwardDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_TransferOfLoansHeldForSaleToPortfolioLoans1": {
     "auth_ref": [
      "r105",
      "r106",
      "r107"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value of loans held-for-sale transferred to loans held in the entity's portfolio in noncash transactions.",
        "label": "Transfer Of Loans Held For Sale To Portfolio Loans1",
        "terseLabel": "Transfer of assets from held for sale to held for investment"
       }
      }
     },
     "localname": "TransferOfLoansHeldForSaleToPortfolioLoans1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TransferOfPortfolioLoansAndLeasesToHeldForSale1": {
     "auth_ref": [
      "r105",
      "r106",
      "r107"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value of loans and leases held in the entity's portfolio transferred to loans and leases held-for-sale in noncash transactions.",
        "label": "Transfer Of Portfolio Loans And Leases To Held For Sale1",
        "terseLabel": "Transfer of assets from held for investment to held for sale"
       }
      }
     },
     "localname": "TransferOfPortfolioLoansAndLeasesToHeldForSale1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain": {
     "auth_ref": [
      "r445"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Instrument or contract that imposes a contractual obligation to deliver cash or another financial instrument or to exchange other financial instruments on potentially unfavorable terms and conveys a contractual right to receive cash or another financial instrument or to exchange other financial instruments on potentially favorable terms.",
        "label": "Transfers And Servicing Of Financial Instruments Types Of Financial Instruments [Domain]",
        "terseLabel": "Financial Instruments"
       }
      }
     },
     "localname": "TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfFHLBBalancesParentheticalDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureDerivativeFinancialInstrumentsGainsLossesOfFairValueHedgesRecognizedAsInterestExpenseDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansSummaryOfRecordedInvestmentsOfModificationsDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_TreasuryStockMember": {
     "auth_ref": [
      "r37",
      "r306"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Shares of an entity that have been repurchased by the entity. This stock has no voting rights and receives no dividends. Note that treasury stock may be recorded at its total cost or separately as par (or stated) value and additional paid in capital. Classified within stockholders' equity if nonredeemable or redeemable solely at the option of the issuer. Classified within temporary equity if redemption is outside the control of the issuer.",
        "label": "Treasury Stock [Member]",
        "terseLabel": "Treasury Stock, at Cost",
        "verboseLabel": "Less Treasury"
       }
      }
     },
     "localname": "TreasuryStockMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureStockholderSEquityScheduleOfCommonStockActivityDetails",
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_TreasuryStockShares": {
     "auth_ref": [
      "r37",
      "r306"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.",
        "label": "Treasury Stock Shares",
        "terseLabel": "Treasury stock, shares at cost (in shares)"
       }
      }
     },
     "localname": "TreasuryStockShares",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_TreasuryStockValue": {
     "auth_ref": [
      "r37",
      "r306",
      "r309"
     ],
     "calculation": {
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 10090.0,
       "parentTag": "cit_CommonStockholdersEquityAttributableToParent",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount allocated to treasury stock. Treasury stock is common and preferred shares of an entity that were issued, repurchased by the entity, and are held in its treasury.",
        "label": "Treasury Stock Value",
        "negatedLabel": "Treasury stock: 64,648,829 shares at March 31, 2020 and 67,445,723 shares at December 31, 2019 at cost"
       }
      }
     },
     "localname": "TreasuryStockValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TroubledDebtRestructuringsOnFinancingReceivablesTableTextBlock": {
     "auth_ref": [
      "r164",
      "r165"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of financing receivable modified as troubled debt restructuring.",
        "label": "Troubled Debt Restructurings On Financing Receivables Table [Text Block]",
        "terseLabel": "Schedule Of Recorded Investments For TDRs"
       }
      }
     },
     "localname": "TroubledDebtRestructuringsOnFinancingReceivablesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_TypeOfAdoptionMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Adoption and early adoption of sources of change to generally accepted accounting principles (GAAP) in the United States. The FASB released the FASB Accounting Standards Codification as the authoritative source of literature effective for interim and annual periods ending after September 15, 2009. As part of the Codification process, the FASB issues Accounting Standards Updates to amend the Codification but otherwise the Accounting Standards Updates are not authoritative in their own right. All previous accounting standards (such as FASB Statements of Financial Accounting Standards, FASB Interpretations, FASB Staff Positions, Emerging Issues Task Force Consensuses, other pronouncements of the FASB or other designated bodies, or other forms of GAAP are considered accounting pronouncements) were superseded upon the adoption of the Codification. For an interim period, references to the superseded standards are included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.",
        "label": "Type Of Adoption [Member]",
        "terseLabel": "Type of Adoption"
       }
      }
     },
     "localname": "TypeOfAdoptionMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureLoansLoansOnNonAccrualStatusDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureRegulatoryCapitalNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_USGovernmentAgenciesDebtSecuritiesMember": {
     "auth_ref": [
      "r311",
      "r456"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debentures, notes, and other debt securities issued by US government agencies, for example, but not limited to, Government National Mortgage Association (GNMA or Ginnie Mae). Excludes US treasury securities and debt issued by government-sponsored Enterprises (GSEs), for example, but is not limited to, Federal Home Loan Mortgage Corporation (FHLMC or Freddie Mac), Federal National Mortgage Association (FNMA or Fannie Mae), and the Federal Home Loan Bank (FHLB).",
        "label": "U S Government Agencies Debt Securities [Member]",
        "terseLabel": "U.S. government/sponsored agency obligations"
       }
      }
     },
     "localname": "USGovernmentAgenciesDebtSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAFSAndHTMEstimatedUnrealizedLossesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_USStatesAndPoliticalSubdivisionsMember": {
     "auth_ref": [
      "r311",
      "r528"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Bonds or similar securities issued by state, city, or local US governments or the agencies operated by state, city, or local governments. Debt securities issued by state governments may include bond issuances of US state authorities including, for example, but not limited to, housing authorities, dormitory authorities, and general obligations while debt securities issued by political subdivisions of US states would include, for example, debt issuances by county, borough, city, or municipal governments.",
        "label": "U S States And Political Subdivisions [Member]",
        "verboseLabel": "State &amp; municipal bonds"
       }
      }
     },
     "localname": "USStatesAndPoliticalSubdivisionsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_USTreasurySecuritiesMember": {
     "auth_ref": [
      "r311",
      "r315",
      "r456"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This category includes information about debt securities issued by the United States Department of the Treasury and backed by the United States government. Such securities primarily consist of treasury bills (short-term maturities - one year or less), treasury notes (intermediate term maturities - two to ten years), and treasury bonds (long-term maturities - ten to thirty years).",
        "label": "U S Treasury Securities [Member]",
        "terseLabel": "U.S. Treasury securities"
       }
      }
     },
     "localname": "USTreasurySecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfAFSAndHTMSecuritiesDetails",
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueMaturitiesWithChangesRecordedInNetIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_UnderlyingAssetClassAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by underlying asset class.",
        "label": "Underlying Asset Class [Axis]",
        "terseLabel": "Underlying Asset Class"
       }
      }
     },
     "localname": "UnderlyingAssetClassAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_UnderlyingAssetClassDomain": {
     "auth_ref": [
      "r385"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Major types of referenced/underlying asset classes (for example, corporate debt, sovereign debt, and structured finance).",
        "label": "Underlying Asset Class [Domain]",
        "terseLabel": "Underlying Asset Class"
       }
      }
     },
     "localname": "UnderlyingAssetClassDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_UnrealizedGainLossOnInvestmentsTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of unrealized gains and losses on investments.",
        "label": "Unrealized Gain Loss On Investments Table [Text Block]",
        "terseLabel": "Schedule of Debt Securities AFS - Estimated Unrealized Losses"
       }
      }
     },
     "localname": "UnrealizedGainLossOnInvestmentsTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureInvestmentSecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_UnsecuredDebt": {
     "auth_ref": [
      "r20",
      "r452",
      "r516"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).",
        "label": "Unsecured Debt",
        "terseLabel": "Unsecured borrowings"
       }
      }
     },
     "localname": "UnsecuredDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_UnsecuredDebtMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt obligation not collateralized by pledge of, mortgage of or other lien on the entity's assets.",
        "label": "Unsecured Debt [Member]",
        "terseLabel": "Senior unsecured"
       }
      }
     },
     "localname": "UnsecuredDebtMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsScheduleOfLongTermBorrowingsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ValuationTechniqueAxis": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by valuation approach and technique.",
        "label": "Valuation Technique [Axis]",
        "terseLabel": "Valuation Approach and Technique"
       }
      }
     },
     "localname": "ValuationTechniqueAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ValuationTechniqueDiscountedCashFlowMember": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Valuation technique calculating present value of future cash flows.",
        "label": "Valuation Technique Discounted Cash Flow [Member]",
        "terseLabel": "Discounted Cash Flow"
       }
      }
     },
     "localname": "ValuationTechniqueDiscountedCashFlowMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ValuationTechniqueDomain": {
     "auth_ref": [
      "r394"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Valuation approach and technique.",
        "label": "Valuation Technique [Domain]",
        "terseLabel": "Valuation Approach and Technique"
       }
      }
     },
     "localname": "ValuationTechniqueDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsRecurringDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis": {
     "auth_ref": [
      "r350",
      "r353",
      "r356"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by category of Variable Interest Entity (VIE).",
        "label": "Variable Interest Entities By Classification Of Entity [Axis]",
        "terseLabel": "Variable Interest Entities"
       }
      }
     },
     "localname": "VariableInterestEntitiesByClassificationOfEntityAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_VariableInterestEntityDisclosureTextBlock": {
     "auth_ref": [
      "r361"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for a variable interest entity (VIE), including but not limited to, judgments and assumptions in determining whether to consolidate and in identifying the primary beneficiary, gain (loss) recognized on the initial consolidation of the VIE, terms of arrangements, amounts and classification of the VIE's assets and liabilities, and the entity's maximum exposure to loss.",
        "label": "Variable Interest Entity Disclosure [Text Block]",
        "terseLabel": "VARIABLE INTEREST ENTITIES"
       }
      }
     },
     "localname": "VariableInterestEntityDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntities"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount": {
     "auth_ref": [
      "r352",
      "r355"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).",
        "label": "Variable Interest Entity Entity Maximum Loss Exposure Amount",
        "terseLabel": "Maximum loss exposure"
       }
      }
     },
     "localname": "VariableInterestEntityEntityMaximumLossExposureAmount",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_VariableInterestEntityLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Variable Interest Entity [Line Items]",
        "terseLabel": "Variable Interest Entity [Line Items]"
       }
      }
     },
     "localname": "VariableInterestEntityLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountAssets": {
     "auth_ref": [
      "r351"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.",
        "label": "Variable Interest Entity Nonconsolidated Carrying Amount Assets",
        "terseLabel": "Total Assets"
       }
      }
     },
     "localname": "VariableInterestEntityNonconsolidatedCarryingAmountAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountLiabilities": {
     "auth_ref": [
      "r351"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Carrying amount of the liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.",
        "label": "Variable Interest Entity Nonconsolidated Carrying Amount Liabilities",
        "terseLabel": "Total Liabilities"
       }
      }
     },
     "localname": "VariableInterestEntityNonconsolidatedCarryingAmountLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureVariableInterestEntitiesAssetsAndLiabilitiesInUnconsolidatedViesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_VariableRateAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of variable rate.",
        "label": "Variable Rate [Axis]",
        "terseLabel": "Variable Rate"
       }
      }
     },
     "localname": "VariableRateAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_VariableRateDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Interest rate that fluctuates over time as a result of an underlying benchmark interest rate or index.",
        "label": "Variable Rate [Domain]",
        "terseLabel": "Variable Rate"
       }
      }
     },
     "localname": "VariableRateDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/DisclosureBorrowingsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding": {
     "auth_ref": [
      "r123",
      "r128"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.",
        "label": "Weighted Average Number Of Diluted Shares Outstanding",
        "terseLabel": "Diluted"
       }
      }
     },
     "localname": "WeightedAverageNumberOfDilutedSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_WeightedAverageNumberOfSharesOutstandingBasic": {
     "auth_ref": [
      "r121",
      "r128"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.",
        "label": "Weighted Average Number Of Shares Outstanding Basic",
        "terseLabel": "Basic"
       }
      }
     },
     "localname": "WeightedAverageNumberOfSharesOutstandingBasic",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://www.cit.com/20200331/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncomeUnaudited"
     ],
     "xbrltype": "sharesItemType"
    }
   },
   "unitCount": 9
  }
 },
 "std_ref": {
  "r0": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=SL51721491-107759"
  },
  "r1": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=SL51721494-107759"
  },
  "r10": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=d3e1361-107760"
  },
  "r100": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585"
  },
  "r101": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585"
  },
  "r102": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3044-108585"
  },
  "r103": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3095-108585"
  },
  "r104": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=d3e4297-108586"
  },
  "r105": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586"
  },
  "r106": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586"
  },
  "r107": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586"
  },
  "r108": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=SL98516268-108586"
  },
  "r109": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790"
  },
  "r11": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721673-107760"
  },
  "r110": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(h))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690"
  },
  "r111": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(m)(2)(i))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690"
  },
  "r112": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08.(e),(f))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690"
  },
  "r113": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08.(h)(2))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690"
  },
  "r114": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.12-04(a))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690"
  },
  "r115": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.12-04.(a))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690"
  },
  "r116": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "235",
   "URI": "http://asc.fasb.org/topic&trid=2122369"
  },
  "r117": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(3)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r118": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r119": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794"
  },
  "r12": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(1)",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721673-107760"
  },
  "r120": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794"
  },
  "r121": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=117326831&loc=d3e1448-109256"
  },
  "r122": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=117326831&loc=d3e1377-109256"
  },
  "r123": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=117326831&loc=d3e1505-109256"
  },
  "r124": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=117326831&loc=d3e1252-109256"
  },
  "r125": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "60B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=117326831&loc=SL5780133-109256"
  },
  "r126": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "60B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=117326831&loc=SL5780133-109256"
  },
  "r127": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=117326831&loc=d3e1337-109256"
  },
  "r128": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257"
  },
  "r129": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257"
  },
  "r13": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)(2)",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721675-107760"
  },
  "r130": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "52",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=117327953&loc=d3e4984-109258"
  },
  "r131": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "270",
   "URI": "http://asc.fasb.org/extlink&oid=118952077&loc=SL77927221-108306"
  },
  "r132": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "275",
   "URI": "http://asc.fasb.org/topic&trid=2134479"
  },
  "r133": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "21",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8721-108599"
  },
  "r134": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599"
  },
  "r135": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599"
  },
  "r136": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599"
  },
  "r137": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599"
  },
  "r138": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8813-108599"
  },
  "r139": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8906-108599"
  },
  "r14": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(2)",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721675-107760"
  },
  "r140": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8933-108599"
  },
  "r141": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8475-108599"
  },
  "r142": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "280",
   "URI": "http://asc.fasb.org/topic&trid=2134510"
  },
  "r143": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522"
  },
  "r144": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118952595&loc=d3e4437-111522"
  },
  "r145": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5162-111524"
  },
  "r146": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524"
  },
  "r147": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524"
  },
  "r148": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524"
  },
  "r149": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(3)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524"
  },
  "r15": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=26872618&loc=d3e7436-122677"
  },
  "r150": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(4)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524"
  },
  "r151": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(g)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524"
  },
  "r152": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524"
  },
  "r153": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524"
  },
  "r154": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953550-111524"
  },
  "r155": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953550-111524"
  },
  "r156": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(3)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524"
  },
  "r157": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(4)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524"
  },
  "r158": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b,d,e)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524"
  },
  "r159": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524"
  },
  "r16": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "205",
   "URI": "http://asc.fasb.org/topic&trid=2122149"
  },
  "r160": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524"
  },
  "r161": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524"
  },
  "r162": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953659-111524"
  },
  "r163": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5066-111524"
  },
  "r164": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "33",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524"
  },
  "r165": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "34",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953682-111524"
  },
  "r166": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "35",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL49126937-111524"
  },
  "r167": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524"
  },
  "r168": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5093-111524"
  },
  "r169": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524"
  },
  "r17": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(12))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r170": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524"
  },
  "r171": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524"
  },
  "r172": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=SL6953401-111524"
  },
  "r173": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118936363&loc=d3e5144-111524"
  },
  "r174": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 4.E)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707"
  },
  "r175": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/subtopic&trid=2196772"
  },
  "r176": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "15",
   "SubTopic": "30",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118938799&loc=d3e13503-111538"
  },
  "r177": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)(2)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118939070&loc=d3e15032-111544"
  },
  "r178": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(b)(2)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118939070&loc=d3e15032-111544"
  },
  "r179": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "30",
   "Topic": "310",
   "URI": "http://asc.fasb.org/subtopic&trid=2196854"
  },
  "r18": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(17))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r180": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118939409&loc=d3e18794-111554"
  },
  "r181": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118939409&loc=d3e18845-111554"
  },
  "r182": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "310",
   "URI": "http://asc.fasb.org/topic&trid=2196771"
  },
  "r183": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "35",
   "Publisher": "FASB",
   "Section": "35",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118985780&loc=d3e25362-111560"
  },
  "r184": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562"
  },
  "r185": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=SL6283291-111563"
  },
  "r186": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563"
  },
  "r187": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(aa)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563"
  },
  "r188": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563"
  },
  "r189": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563"
  },
  "r19": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(2))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r190": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563"
  },
  "r191": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27198-111563"
  },
  "r192": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27198-111563"
  },
  "r193": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27198-111563"
  },
  "r194": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27198-111563"
  },
  "r195": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563"
  },
  "r196": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563"
  },
  "r197": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118939692&loc=SL6284393-111563"
  },
  "r198": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "320",
   "URI": "http://asc.fasb.org/topic&trid=2196928"
  },
  "r199": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "321",
   "URI": "http://asc.fasb.org/extlink&oid=116654751&loc=SL75117539-209714"
  },
  "r2": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1C",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=SL51721501-107759"
  },
  "r20": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(22))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r200": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "321",
   "URI": "http://asc.fasb.org/extlink&oid=116654751&loc=SL75117546-209714"
  },
  "r201": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "321",
   "URI": "http://asc.fasb.org/topic&trid=75115024"
  },
  "r202": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "323",
   "URI": "http://asc.fasb.org/extlink&oid=109237563&loc=d3e33775-111570"
  },
  "r203": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(2)",
   "Topic": "323",
   "URI": "http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571"
  },
  "r204": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "323",
   "URI": "http://asc.fasb.org/topic&trid=2196965"
  },
  "r205": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "325",
   "URI": "http://asc.fasb.org/topic&trid=2197064"
  },
  "r206": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118950378&loc=SL82887624-210437"
  },
  "r207": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955202&loc=SL82895884-210446"
  },
  "r208": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955202&loc=SL82919202-210446"
  },
  "r209": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919244-210447"
  },
  "r21": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(25))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r210": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447"
  },
  "r211": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447"
  },
  "r212": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447"
  },
  "r213": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447"
  },
  "r214": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(e)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447"
  },
  "r215": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(f)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447"
  },
  "r216": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447"
  },
  "r217": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919253-210447"
  },
  "r218": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447"
  },
  "r219": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447"
  },
  "r22": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(27))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r220": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447"
  },
  "r221": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447"
  },
  "r222": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447"
  },
  "r223": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "19",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919265-210447"
  },
  "r224": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "19",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919265-210447"
  },
  "r225": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "19",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919265-210447"
  },
  "r226": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "19",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919265-210447"
  },
  "r227": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919230-210447"
  },
  "r228": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919230-210447"
  },
  "r229": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919232-210447"
  },
  "r23": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(28))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r230": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82921830-210448"
  },
  "r231": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82921833-210448"
  },
  "r232": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82921835-210448"
  },
  "r233": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(e)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82921835-210448"
  },
  "r234": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(e)(1)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82921835-210448"
  },
  "r235": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(e)(2)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82921835-210448"
  },
  "r236": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82921842-210448"
  },
  "r237": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82921842-210448"
  },
  "r238": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(d)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82921842-210448"
  },
  "r239": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "79",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82922352-210448"
  },
  "r24": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(29))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r240": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "80",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955255&loc=SL82922355-210448"
  },
  "r241": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/subtopic&trid=82887181"
  },
  "r242": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454"
  },
  "r243": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955579&loc=SL82922888-210455"
  },
  "r244": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955579&loc=SL82922890-210455"
  },
  "r245": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955579&loc=SL82922895-210455"
  },
  "r246": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955579&loc=SL82922900-210455"
  },
  "r247": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118942371&loc=SL82922954-210456"
  },
  "r248": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/subtopic&trid=82887182"
  },
  "r249": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266"
  },
  "r25": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(3))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r250": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=99380562&loc=d3e13777-109266"
  },
  "r251": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975"
  },
  "r252": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267"
  },
  "r253": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(e)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267"
  },
  "r254": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267"
  },
  "r255": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=108376223&loc=SL108378252-109267"
  },
  "r256": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=108376223&loc=d3e13854-109267"
  },
  "r257": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=108376223&loc=d3e13854-109267"
  },
  "r258": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "35",
   "SubTopic": "30",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=108376495&loc=d3e15372-109273"
  },
  "r259": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274"
  },
  "r26": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30)(a)(1))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r260": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275"
  },
  "r261": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)(1)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275"
  },
  "r262": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(d)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275"
  },
  "r263": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275"
  },
  "r264": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)(1)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275"
  },
  "r265": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)(2)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275"
  },
  "r266": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)(3)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275"
  },
  "r267": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(d)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275"
  },
  "r268": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "350",
   "URI": "http://asc.fasb.org/topic&trid=2144416"
  },
  "r269": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "15",
   "SubTopic": "10",
   "Subparagraph": "(b)(2)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=77912953&loc=d3e400-110220"
  },
  "r27": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30)(a)(3))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r270": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228"
  },
  "r271": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229"
  },
  "r272": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230"
  },
  "r273": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230"
  },
  "r274": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869"
  },
  "r275": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 5.P.4(d))",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747"
  },
  "r276": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "440",
   "URI": "http://asc.fasb.org/extlink&oid=77929361&loc=d3e25218-109307"
  },
  "r277": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "440",
   "URI": "http://asc.fasb.org/topic&trid=2144648"
  },
  "r278": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "05",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=99385795&loc=d3e12631-108344"
  },
  "r279": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=118942415&loc=d3e14326-108349"
  },
  "r28": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r280": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=118942415&loc=d3e14615-108349"
  },
  "r281": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=118942415&loc=d3e14394-108349"
  },
  "r282": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=118942415&loc=d3e14435-108349"
  },
  "r283": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=118942415&loc=d3e14435-108349"
  },
  "r284": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=118942415&loc=d3e14453-108349"
  },
  "r285": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=118942415&loc=d3e14472-108349"
  },
  "r286": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=118942415&loc=d3e14557-108349"
  },
  "r287": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/subtopic&trid=2127163"
  },
  "r288": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "30",
   "Topic": "450",
   "URI": "http://asc.fasb.org/subtopic&trid=2127197"
  },
  "r289": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "460",
   "URI": "http://asc.fasb.org/extlink&oid=118956080&loc=d3e11927-110247"
  },
  "r29": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(31))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r290": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "460",
   "URI": "http://asc.fasb.org/extlink&oid=118943654&loc=d3e12021-110248"
  },
  "r291": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "460",
   "URI": "http://asc.fasb.org/extlink&oid=118943654&loc=d3e12053-110248"
  },
  "r292": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(4)",
   "Topic": "460",
   "URI": "http://asc.fasb.org/extlink&oid=118943654&loc=d3e12069-110248"
  },
  "r293": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "460",
   "URI": "http://asc.fasb.org/extlink&oid=68068213&loc=d3e12565-110249"
  },
  "r294": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601"
  },
  "r295": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=6802200&loc=SL6230698-112601"
  },
  "r296": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(3)",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870"
  },
  "r297": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "40",
   "SubTopic": "50",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=117329964&loc=d3e12317-112629"
  },
  "r298": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "40",
   "SubTopic": "50",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=117329964&loc=d3e12355-112629"
  },
  "r299": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "470",
   "URI": "http://asc.fasb.org/topic&trid=2208564"
  },
  "r3": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1D",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=SL51721503-107759"
  },
  "r30": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(32))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r300": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644"
  },
  "r301": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644"
  },
  "r302": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644"
  },
  "r303": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644"
  },
  "r304": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644"
  },
  "r305": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.3-04)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770"
  },
  "r306": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655"
  },
  "r307": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656"
  },
  "r308": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=6405834&loc=d3e23309-112656"
  },
  "r309": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=6405834&loc=d3e23315-112656"
  },
  "r31": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19(a))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r310": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "505",
   "URI": "http://asc.fasb.org/topic&trid=2208762"
  },
  "r311": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(ii)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r312": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(01)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r313": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(j)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r314": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(n)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r315": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921"
  },
  "r316": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5047-113901"
  },
  "r317": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r318": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319"
  },
  "r319": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319"
  },
  "r32": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19(b),22(b))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r320": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319"
  },
  "r321": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 6.I.7)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817"
  },
  "r322": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=109238882&loc=d3e39076-109324"
  },
  "r323": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=109238882&loc=d3e38679-109324"
  },
  "r324": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(d)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=109238882&loc=d3e38679-109324"
  },
  "r325": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "740",
   "URI": "http://asc.fasb.org/topic&trid=2144680"
  },
  "r326": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463"
  },
  "r327": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)(2)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463"
  },
  "r328": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)(3)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463"
  },
  "r329": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463"
  },
  "r33": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r330": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=79982066&loc=d3e1486-128463"
  },
  "r331": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "37",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=116868840&loc=d3e2207-128464"
  },
  "r332": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(1)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=116869197&loc=d3e4845-128472"
  },
  "r333": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=116869197&loc=d3e4845-128472"
  },
  "r334": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=116869197&loc=d3e4845-128472"
  },
  "r335": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=77890550&loc=d3e5263-128473"
  },
  "r336": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=77890550&loc=d3e5333-128473"
  },
  "r337": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "30",
   "SubTopic": "30",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477"
  },
  "r338": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "30",
   "SubTopic": "30",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477"
  },
  "r339": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(b)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479"
  },
  "r34": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19-26)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r340": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(b)(1)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479"
  },
  "r341": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(b)(4)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479"
  },
  "r342": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=108774443&loc=SL4568447-111683"
  },
  "r343": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=108774443&loc=SL4568740-111683"
  },
  "r344": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "18",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=108774443&loc=SL4613673-111683"
  },
  "r345": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "19",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=108774443&loc=SL4569616-111683"
  },
  "r346": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=108774443&loc=SL4569643-111683"
  },
  "r347": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=109239629&loc=d3e5614-111684"
  },
  "r348": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(3)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684"
  },
  "r349": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c),(3)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684"
  },
  "r35": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.22 (b))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r350": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=118582676&loc=d3e5710-111685"
  },
  "r351": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "a",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=118582676&loc=d3e5728-111685"
  },
  "r352": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "b",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=118582676&loc=d3e5728-111685"
  },
  "r353": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=118582676&loc=d3e5728-111685"
  },
  "r354": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=118582676&loc=SL6759159-111685"
  },
  "r355": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=118582676&loc=d3e5747-111685"
  },
  "r356": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=118582676&loc=d3e5747-111685"
  },
  "r357": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=118582676&loc=SL6228884-111685"
  },
  "r358": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4I",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116874947&loc=SL4590271-111686"
  },
  "r359": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.3A-02)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116822174&loc=d3e355033-122828"
  },
  "r36": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.22)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r360": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.3A-03)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116822174&loc=d3e355100-122828"
  },
  "r361": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "810",
   "URI": "http://asc.fasb.org/topic&trid=2197479"
  },
  "r362": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "83",
   "Publisher": "FASB",
   "Section": "15",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=117415099&loc=d3e34841-113949"
  },
  "r363": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959"
  },
  "r364": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959"
  },
  "r365": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)(i)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=d3e41620-113959"
  },
  "r366": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)(iii)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=d3e41620-113959"
  },
  "r367": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=d3e41620-113959"
  },
  "r368": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959"
  },
  "r369": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959"
  },
  "r37": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.29,30)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r370": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(1)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959"
  },
  "r371": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a),(c)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959"
  },
  "r372": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959"
  },
  "r373": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959"
  },
  "r374": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959"
  },
  "r375": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959"
  },
  "r376": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959"
  },
  "r377": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4CCC",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL109998896-113959"
  },
  "r378": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624177-113959"
  },
  "r379": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(2)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624177-113959"
  },
  "r38": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.29-31)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r380": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(6)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624177-113959"
  },
  "r381": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624177-113959"
  },
  "r382": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624177-113959"
  },
  "r383": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4E",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624181-113959"
  },
  "r384": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4F",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5624186-113959"
  },
  "r385": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4K",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5708775-113959"
  },
  "r386": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4K",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(4)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=SL5708775-113959"
  },
  "r387": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109980867&loc=d3e41678-113959"
  },
  "r388": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "182",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=116861445&loc=SL5629052-113961"
  },
  "r389": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "25",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=109977999&loc=d3e76258-113986"
  },
  "r39": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.3,4)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r390": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "815",
   "URI": "http://asc.fasb.org/topic&trid=2229140"
  },
  "r391": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r392": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r393": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bb)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r394": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bbb)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r395": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bbb)(1)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r396": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bbb)(2)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r397": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r398": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r399": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1a)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r4": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=d3e957-107759"
  },
  "r40": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.8)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r400": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r401": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r402": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r403": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r404": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19279-110258"
  },
  "r405": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=SL6742756-110258"
  },
  "r406": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=SL6742756-110258"
  },
  "r407": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740"
  },
  "r408": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=116690757&loc=d3e13220-108610"
  },
  "r409": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611"
  },
  "r41": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.8,17)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r410": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=118260190&loc=d3e13467-108611"
  },
  "r411": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=118260190&loc=d3e13476-108611"
  },
  "r412": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612"
  },
  "r413": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "230",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=98513438&loc=d3e33268-110906"
  },
  "r414": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(b,c)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r415": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391"
  },
  "r416": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399"
  },
  "r417": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399"
  },
  "r418": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399"
  },
  "r419": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400"
  },
  "r42": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=49176635&loc=d3e9760-107771"
  },
  "r420": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "25",
   "SubTopic": "20",
   "Topic": "840",
   "URI": "http://asc.fasb.org/extlink&oid=77902458&loc=d3e39896-112707"
  },
  "r421": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "840",
   "URI": "http://asc.fasb.org/extlink&oid=84164653&loc=d3e41551-112718"
  },
  "r422": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "840",
   "URI": "http://asc.fasb.org/extlink&oid=77907235&loc=d3e45152-112736"
  },
  "r423": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977"
  },
  "r424": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977"
  },
  "r425": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888419&loc=SL77918643-209977"
  },
  "r426": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)(3)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980"
  },
  "r427": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(1)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980"
  },
  "r428": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(2)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980"
  },
  "r429": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "53",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971"
  },
  "r43": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312"
  },
  "r430": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888421&loc=SL77919311-209978"
  },
  "r431": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)(2)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=119202524&loc=SL77919372-209981"
  },
  "r432": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(b)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=119202524&loc=SL77919372-209981"
  },
  "r433": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(c)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=119202524&loc=SL77919372-209981"
  },
  "r434": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=119202524&loc=SL77919372-209981"
  },
  "r435": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "50",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888424&loc=SL77920237-209979"
  },
  "r436": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864"
  },
  "r437": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864"
  },
  "r438": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=118948506&loc=d3e107207-111719"
  },
  "r439": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=118948506&loc=d3e107207-111719"
  },
  "r44": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312"
  },
  "r440": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=118948506&loc=d3e107207-111719"
  },
  "r441": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=118948506&loc=d3e107207-111719"
  },
  "r442": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=118948506&loc=SL51823488-111719"
  },
  "r443": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(b)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729"
  },
  "r444": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(b)(1)(i)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729"
  },
  "r445": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746"
  },
  "r446": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "340",
   "Topic": "928",
   "URI": "http://asc.fasb.org/extlink&oid=6473545&loc=d3e61844-108004"
  },
  "r447": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "25",
   "SubTopic": "20",
   "Topic": "940",
   "URI": "http://asc.fasb.org/extlink&oid=68072869&loc=d3e41242-110953"
  },
  "r448": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "320",
   "Topic": "940",
   "URI": "http://asc.fasb.org/subtopic&trid=2176304"
  },
  "r449": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "210",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117340910&loc=d3e59706-112781"
  },
  "r45": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312"
  },
  "r450": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(10))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r451": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(11))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r452": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(16))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r453": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(17))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r454": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(23))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r455": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(3))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r456": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(6)(a)(1))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r457": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(6))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r458": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(7)(d))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r459": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(7))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r46": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(2)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312"
  },
  "r460": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.10)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r461": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.12)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r462": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.13(3)(a))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r463": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.13,16)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r464": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.15)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r465": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.16)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r466": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.2)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r467": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.7(d))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r468": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(19))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r469": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(11))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r47": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(e)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312"
  },
  "r470": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(13))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r471": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(15))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r472": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(20))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r473": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(22))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r474": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(23))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r475": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.1)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r476": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.1-5)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r477": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.10)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r478": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.11)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r479": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.12)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r48": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313"
  },
  "r480": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.13)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r481": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.14)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r482": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.6)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r483": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.8)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r484": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.9)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260"
  },
  "r485": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "230",
   "Subparagraph": "(b)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6477933&loc=d3e60009-112784"
  },
  "r486": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "320",
   "Subparagraph": "(a)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75019621&loc=d3e62586-112803"
  },
  "r487": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "320",
   "Subparagraph": "(b)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75019621&loc=d3e62586-112803"
  },
  "r488": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "320",
   "Subparagraph": "(c)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75019621&loc=d3e62586-112803"
  },
  "r489": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "320",
   "Subparagraph": "(d)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75019621&loc=d3e62586-112803"
  },
  "r49": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=99393222&loc=SL20226016-175313"
  },
  "r490": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "320",
   "Topic": "942",
   "URI": "http://asc.fasb.org/subtopic&trid=2209399"
  },
  "r491": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "405",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817"
  },
  "r492": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "405",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=116652737&loc=d3e64164-112818"
  },
  "r493": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "470",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822"
  },
  "r494": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "470",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75038535&loc=d3e64684-112823"
  },
  "r495": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "470",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75038535&loc=d3e64702-112823"
  },
  "r496": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "470",
   "Subparagraph": "(b)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823"
  },
  "r497": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "470",
   "Subparagraph": "(d)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823"
  },
  "r498": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "470",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823"
  },
  "r499": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Subparagraph": "(c)(1)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826"
  },
  "r5": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=SL51721523-107759"
  },
  "r50": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313"
  },
  "r500": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826"
  },
  "r501": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=SL5958569-112826"
  },
  "r502": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826"
  },
  "r503": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=SL5958572-112826"
  },
  "r504": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=SL5958573-112826"
  },
  "r505": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1E",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=SL5958574-112826"
  },
  "r506": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1F",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=SL5958575-112826"
  },
  "r507": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1G",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=SL5958577-112826"
  },
  "r508": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1H",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Subparagraph": "(c)(1)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826"
  },
  "r509": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1H",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Subparagraph": "(c)(2)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826"
  },
  "r51": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=99393222&loc=SL20226003-175313"
  },
  "r510": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1H",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "505",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826"
  },
  "r511": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(16))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r512": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(19))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r513": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(1)(b))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r514": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(10))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r515": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(12))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r516": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(16))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r517": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(19))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r518": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(23)(a)(4))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r519": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(25))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r52": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580"
  },
  "r520": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03.1(h))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r521": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(11))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263"
  },
  "r522": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(18))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263"
  },
  "r523": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(19))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263"
  },
  "r524": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(4))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263"
  },
  "r525": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(8))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263"
  },
  "r526": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04.2)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263"
  },
  "r527": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4H",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=116884468&loc=SL65671331-158438"
  },
  "r528": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "80",
   "Subparagraph": "(e)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=117420044&loc=d3e19393-158473"
  },
  "r529": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12(2)(i))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010"
  },
  "r53": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a),(b),(c)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580"
  },
  "r530": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12C(1)(a))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=50485924&loc=d3e611225-123010"
  },
  "r531": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-13(1))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=50485924&loc=d3e611282-123010"
  },
  "r532": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-15(Column A))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=50485924&loc=d3e611379-123010"
  },
  "r533": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-15)",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=50485924&loc=d3e611379-123010"
  },
  "r534": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "320",
   "Topic": "946",
   "URI": "http://asc.fasb.org/subtopic&trid=2324412"
  },
  "r535": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "948",
   "URI": "http://asc.fasb.org/extlink&oid=6490092&loc=d3e47080-110998"
  },
  "r536": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "948",
   "URI": "http://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998"
  },
  "r537": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "310",
   "Subparagraph": "(SX 210.12-29(Footnote 6))",
   "Topic": "948",
   "URI": "http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014"
  },
  "r538": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "450",
   "Topic": "954",
   "URI": "http://asc.fasb.org/extlink&oid=6491354&loc=d3e6049-115624"
  },
  "r539": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "450",
   "Topic": "954",
   "URI": "http://asc.fasb.org/extlink&oid=6491354&loc=d3e6052-115624"
  },
  "r54": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580"
  },
  "r540": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "360",
   "Subparagraph": "(SX 210.12-28(Footnote 4))",
   "Topic": "970",
   "URI": "http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024"
  },
  "r541": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b"
  },
  "r542": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "d1-1"
  },
  "r543": {
   "Name": "Form 10-Q",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "13",
   "Subsection": "a-13"
  },
  "r544": {
   "Name": "Forms 10-K, 10-Q, 20-F",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "13",
   "Subsection": "a-1-"
  },
  "r545": {
   "Name": "Industry Guide",
   "Number": "3",
   "Paragraph": "D-E",
   "Publisher": "SEC",
   "Section": "V"
  },
  "r546": {
   "Name": "Regulation 12B",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b-2"
  },
  "r547": {
   "Name": "Regulation S-T",
   "Number": "232",
   "Publisher": "SEC",
   "Section": "405"
  },
  "r55": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580"
  },
  "r56": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(g)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580"
  },
  "r57": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(h)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580"
  },
  "r58": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(i),(j),(k)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580"
  },
  "r59": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(i-k)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580"
  },
  "r6": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=SL51721525-107759"
  },
  "r60": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580"
  },
  "r61": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=d3e637-108580"
  },
  "r62": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=d3e640-108580"
  },
  "r63": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=d3e681-108580"
  },
  "r64": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580"
  },
  "r65": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL34724394-108580"
  },
  "r66": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580"
  },
  "r67": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580"
  },
  "r68": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580"
  },
  "r69": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669625-108580"
  },
  "r7": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=d3e1012-107759"
  },
  "r70": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669625-108580"
  },
  "r71": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=d3e557-108580"
  },
  "r72": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118951672&loc=d3e1436-108581"
  },
  "r73": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(1)(e))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868656-224227"
  },
  "r74": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(13))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868656-224227"
  },
  "r75": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(210.5-03(11))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r76": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(10))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r77": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(20))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r78": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(21))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r79": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.13)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r8": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=d3e1361-107760"
  },
  "r80": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.2)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r81": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.7(a),(b))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r82": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.8)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r83": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.9)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r84": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585"
  },
  "r85": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585"
  },
  "r86": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585"
  },
  "r87": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585"
  },
  "r88": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585"
  },
  "r89": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585"
  },
  "r9": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=d3e1361-107760"
  },
  "r90": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585"
  },
  "r91": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585"
  },
  "r92": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585"
  },
  "r93": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3367-108585"
  },
  "r94": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "21",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3461-108585"
  },
  "r95": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "21C",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=SL94080552-108585"
  },
  "r96": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "24",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3521-108585"
  },
  "r97": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3536-108585"
  },
  "r98": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3536-108585"
  },
  "r99": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585"
  }
 },
 "version": "2.1"
}
