{
 "instance": {
  "inbk-20200630.htm": {
   "axisCustom": 1,
   "axisStandard": 31,
   "contextCount": 649,
   "dts": {
    "calculationLink": {
     "local": [
      "inbk-20200630_cal.xml"
     ]
    },
    "definitionLink": {
     "local": [
      "inbk-20200630_def.xml"
     ],
     "remote": [
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-eedm-def-2020-01-31.xml",
      "http://xbrl.fasb.org/srt/2020/elts/srt-eedm1-def-2020-01-31.xml"
     ]
    },
    "inline": {
     "local": [
      "inbk-20200630.htm"
     ]
    },
    "labelLink": {
     "local": [
      "inbk-20200630_lab.xml"
     ],
     "remote": [
      "https://xbrl.sec.gov/dei/2019/dei-doc-2019-01-31.xml",
      "http://xbrl.fasb.org/srt/2020/elts/srt-doc-2020-01-31.xml",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-doc-2020-01-31.xml"
     ]
    },
    "presentationLink": {
     "local": [
      "inbk-20200630_pre.xml"
     ]
    },
    "referenceLink": {
     "remote": [
      "http://xbrl.fasb.org/srt/2020/elts/srt-ref-2020-01-31.xml",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-ref-2020-01-31.xml",
      "https://xbrl.sec.gov/dei/2019/dei-ref-2019-01-31.xml"
     ]
    },
    "schema": {
     "local": [
      "inbk-20200630.xsd"
     ],
     "remote": [
      "http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd",
      "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/dtr/type/numeric-2009-12-16.xsd",
      "http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd",
      "http://www.xbrl.org/2005/xbrldt-2005.xsd",
      "http://www.xbrl.org/2006/ref-2006-02-27.xsd",
      "http://xbrl.fasb.org/srt/2020/elts/srt-types-2020-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-roles-2020-01-31.xsd",
      "http://xbrl.fasb.org/srt/2020/elts/srt-roles-2020-01-31.xsd",
      "https://xbrl.sec.gov/country/2020/country-2020-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-types-2020-01-31.xsd",
      "https://xbrl.sec.gov/currency/2020/currency-2020-01-31.xsd",
      "https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd",
      "http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd",
      "http://www.xbrl.org/lrr/role/net-2009-12-16.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/2020/elts/us-parts-codification-2020-01-31.xsd"
     ]
    }
   },
   "elementCount": 643,
   "entityCount": 1,
   "hidden": {
    "http://fasb.org/us-gaap/2020-01-31": 42,
    "http://www.firstib.com/20200630": 16,
    "http://xbrl.sec.gov/dei/2019-01-31": 5,
    "total": 63
   },
   "keyCustom": 56,
   "keyStandard": 405,
   "memberCustom": 36,
   "memberStandard": 65,
   "nsprefix": "inbk",
   "nsuri": "http://www.firstib.com/20200630",
   "report": {
    "R1": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "dei:DocumentType",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "document",
     "isDefault": "true",
     "longName": "0001001 - Document - Cover",
     "role": "http://www.firstib.com/role/Cover",
     "shortName": "Cover",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "dei:DocumentType",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R10": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfWeightedAverageNumberOfSharesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NetIncomeLoss",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1004005 - Statement - Condensed Consolidated Statements of Comprehensive Income (Unaudited)",
     "role": "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited",
     "shortName": "Condensed Consolidated Statements of Comprehensive Income (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R11": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i508a4f82db18494d9bb9a35aa00f1c11_I20181231",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquity",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1005006 - Statement - Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited)",
     "role": "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited",
     "shortName": "Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i67da1c36efa04607bf5455f51e16a367_I20181231",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquity",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R12": {
     "firstAnchor": null,
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1006007 - Statement - Consolidated Statements of Shareholders' Equity (Unaudited) (Parenthetical)",
     "role": "http://www.firstib.com/role/ConsolidatedStatementsofShareholdersEquityUnauditedParenthetical",
     "shortName": "Consolidated Statements of Shareholders' Equity (Unaudited) (Parenthetical)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": null
    },
    "R13": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NetIncomeLoss",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1007008 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)",
     "role": "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited",
     "shortName": "Condensed Consolidated Statements of Cash Flows (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:DepreciationDepletionAndAmortization",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R14": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2101101 - Disclosure - Basis of Presentation",
     "role": "http://www.firstib.com/role/BasisofPresentation",
     "shortName": "Basis of Presentation",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R15": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:EarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2104102 - Disclosure - Earnings Per Share",
     "role": "http://www.firstib.com/role/EarningsPerShare",
     "shortName": "Earnings Per Share",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:EarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R16": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2107103 - Disclosure - Securities",
     "role": "http://www.firstib.com/role/Securities",
     "shortName": "Securities",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R17": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2114104 - Disclosure - Loans",
     "role": "http://www.firstib.com/role/Loans",
     "shortName": "Loans",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LoansNotesTradeAndOtherReceivablesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R18": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeasesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2126106 - Disclosure - Leases",
     "role": "http://www.firstib.com/role/Leases",
     "shortName": "Leases",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeasesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R19": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:TransfersAndServicingOfFinancialAssetsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2132108 - Disclosure - Servicing Asset",
     "role": "http://www.firstib.com/role/ServicingAsset",
     "shortName": "Servicing Asset",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:TransfersAndServicingOfFinancialAssetsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R2": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PropertyPlantAndEquipmentDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "document",
     "isDefault": "false",
     "longName": "0103105 - Document - Premises and Equipment",
     "role": "http://www.firstib.com/role/PremisesandEquipment",
     "shortName": "Premises and Equipment",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PropertyPlantAndEquipmentDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R20": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CommitmentsAndContingenciesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2144111 - Disclosure - Commitments and Credit Risk",
     "role": "http://www.firstib.com/role/CommitmentsandCreditRisk",
     "shortName": "Commitments and Credit Risk",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CommitmentsAndContingenciesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R21": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2146112 - Disclosure - Fair Value of Financial Instruments",
     "role": "http://www.firstib.com/role/FairValueofFinancialInstruments",
     "shortName": "Fair Value of Financial Instruments",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R22": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "srt:MortgageLoansOnRealEstateByLoanDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2152113 - Disclosure - Mortgage Banking Activities",
     "role": "http://www.firstib.com/role/MortgageBankingActivities",
     "shortName": "Mortgage Banking Activities",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "srt:MortgageLoansOnRealEstateByLoanDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R23": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ComprehensiveIncomeNoteTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2161115 - Disclosure - Accumulated Other Comprehensive Loss",
     "role": "http://www.firstib.com/role/AccumulatedOtherComprehensiveLoss",
     "shortName": "Accumulated Other Comprehensive Loss",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ComprehensiveIncomeNoteTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R24": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2164116 - Disclosure - Recent Accounting Pronouncements",
     "role": "http://www.firstib.com/role/RecentAccountingPronouncements",
     "shortName": "Recent Accounting Pronouncements",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R25": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock",
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NewAccountingPronouncementsPolicyPolicyTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2202201 - Disclosure - Basis of Presentation (Policies)",
     "role": "http://www.firstib.com/role/BasisofPresentationPolicies",
     "shortName": "Basis of Presentation (Policies)",
     "subGroupType": "policies",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock",
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NewAccountingPronouncementsPolicyPolicyTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R26": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfWeightedAverageNumberOfSharesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2305301 - Disclosure - Earnings Per Share (Tables)",
     "role": "http://www.firstib.com/role/EarningsPerShareTables",
     "shortName": "Earnings Per Share (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfWeightedAverageNumberOfSharesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R27": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2308302 - Disclosure - Securities (Tables)",
     "role": "http://www.firstib.com/role/SecuritiesTables",
     "shortName": "Securities (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R28": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2315303 - Disclosure - Loans (Tables)",
     "role": "http://www.firstib.com/role/LoansTables",
     "shortName": "Loans (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R29": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PropertyPlantAndEquipmentTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2323304 - Disclosure - Premises and Equipment (Tables)",
     "role": "http://www.firstib.com/role/PremisesandEquipmentTables",
     "shortName": "Premises and Equipment (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PropertyPlantAndEquipmentTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R3": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:GoodwillAndIntangibleAssetsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "document",
     "isDefault": "false",
     "longName": "0104107 - Document - Goodwill",
     "role": "http://www.firstib.com/role/Goodwill",
     "shortName": "Goodwill",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:GoodwillAndIntangibleAssetsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R30": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LeaseCostTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2327305 - Disclosure - Leases (Tables)",
     "role": "http://www.firstib.com/role/LeasesTables",
     "shortName": "Leases (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LeaseCostTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R31": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfServicingAssetsAtFairValueTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2333306 - Disclosure - Servicing Asset (Tables)",
     "role": "http://www.firstib.com/role/ServicingAssetTables",
     "shortName": "Servicing Asset (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfServicingAssetsAtFairValueTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R32": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfSubordinatedBorrowingTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2337307 - Disclosure - Subordinated Debt (Tables)",
     "role": "http://www.firstib.com/role/SubordinatedDebtTables",
     "shortName": "Subordinated Debt (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfSubordinatedBorrowingTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R33": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NonvestedRestrictedStockSharesActivityTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2340308 - Disclosure - Benefit Plans (Tables)",
     "role": "http://www.firstib.com/role/BenefitPlansTables",
     "shortName": "Benefit Plans (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NonvestedRestrictedStockSharesActivityTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R34": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueAssetsMeasuredOnRecurringBasisTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2347309 - Disclosure - Fair Value of Financial Instruments (Tables)",
     "role": "http://www.firstib.com/role/FairValueofFinancialInstrumentsTables",
     "shortName": "Fair Value of Financial Instruments (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueAssetsMeasuredOnRecurringBasisTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R35": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfParticipatingMortgageLoansTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2353310 - Disclosure - Mortgage Banking Activities (Tables)",
     "role": "http://www.firstib.com/role/MortgageBankingActivitiesTables",
     "shortName": "Mortgage Banking Activities (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfParticipatingMortgageLoansTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R36": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "inbk:ScheduleOfDerivativeInstrumentsCumulativeBasisAdjustmentsTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2355311 - Disclosure - Derivative Financial Instruments (Tables)",
     "role": "http://www.firstib.com/role/DerivativeFinancialInstrumentsTables",
     "shortName": "Derivative Financial Instruments (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "inbk:ScheduleOfDerivativeInstrumentsCumulativeBasisAdjustmentsTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R37": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
      "reportCount": 1,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2362312 - Disclosure - Accumulated Other Comprehensive Loss (Tables)",
     "role": "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossTables",
     "shortName": "Accumulated Other Comprehensive Loss (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": null
    },
    "R38": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "inbk:NumberOfWhollyOwnedSubsidiaries",
      "reportCount": 1,
      "unique": true,
      "unitRef": "subsidiary",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2403401 - Disclosure - Basis of Presentation (Details)",
     "role": "http://www.firstib.com/role/BasisofPresentationDetails",
     "shortName": "Basis of Presentation (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "inbk:NumberOfWhollyOwnedSubsidiaries",
      "reportCount": 1,
      "unique": true,
      "unitRef": "subsidiary",
      "xsiNil": "false"
     }
    },
    "R39": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfWeightedAverageNumberOfSharesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NetIncomeLoss",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2406402 - Disclosure - Earnings Per Share (Details)",
     "role": "http://www.firstib.com/role/EarningsPerShareDetails",
     "shortName": "Earnings Per Share (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfWeightedAverageNumberOfSharesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "0",
      "lang": "en-US",
      "name": "us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     }
    },
    "R4": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LongTermDebtTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "document",
     "isDefault": "false",
     "longName": "0105109 - Document - Subordinated Debt",
     "role": "http://www.firstib.com/role/SubordinatedDebt",
     "shortName": "Subordinated Debt",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LongTermDebtTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R40": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:DebtSecuritiesAvailableForSaleTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2409403 - Disclosure - Securities (Details)",
     "role": "http://www.firstib.com/role/SecuritiesDetails",
     "shortName": "Securities (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R41": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i6b48beabd37e4e5f8410a873f6cf91d4_I20200301",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "inbk:DebtSecuritiesAvailableForSaleNumberOfSecuritiesTransferredToHeldForSale",
      "reportCount": 1,
      "unique": true,
      "unitRef": "security",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2410404 - Disclosure - Securities (Details Textual)",
     "role": "http://www.firstib.com/role/SecuritiesDetailsTextual",
     "shortName": "Securities (Details Textual)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i6b48beabd37e4e5f8410a873f6cf91d4_I20200301",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "inbk:DebtSecuritiesAvailableForSaleNumberOfSecuritiesTransferredToHeldForSale",
      "reportCount": 1,
      "unique": true,
      "unitRef": "security",
      "xsiNil": "false"
     }
    },
    "R42": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:DebtSecuritiesAvailableForSaleTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2411405 - Disclosure - Securities - Carrying Value (Details)",
     "role": "http://www.firstib.com/role/SecuritiesCarryingValueDetails",
     "shortName": "Securities - Carrying Value (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:DebtSecuritiesAvailableForSaleTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R43": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2412406 - Disclosure - Securities - Gross Unrealized Losses and Fair Value (Details)",
     "role": "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails",
     "shortName": "Securities - Gross Unrealized Losses and Fair Value (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R44": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DebtSecuritiesAvailableForSaleRealizedGainLoss",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2413407 - Disclosure - Securities Securities - Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (Details)",
     "role": "http://www.firstib.com/role/SecuritiesSecuritiesAmountsReclassifiedfromAccumulatedOtherComprehensiveIncomeLossDetails",
     "shortName": "Securities Securities - Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R45": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "inbk:AllowanceForCreditLossesOnFinancingReceivablesPortfolioSegmentTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LoansAndLeasesReceivableGrossCarryingAmount",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2416408 - Disclosure - Loans - Categories (Details)",
     "role": "http://www.firstib.com/role/LoansCategoriesDetails",
     "shortName": "Loans - Categories (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:UnamortizedLoanCommitmentAndOriginationFeesAndUnamortizedDiscountsOrPremiums",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R46": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0a6b9589e2674cf69256f9ca0aaba7f4_I20200331",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LoansAndLeasesReceivableAllowance",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2417409 - Disclosure - Loans - Change in the Balances of the ALLL (Details)",
     "role": "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
     "shortName": "Loans - Change in the Balances of the ALLL (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:ProvisionForLoanAndLeaseLosses",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R47": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "inbk:AllowanceForCreditLossesOnFinancingReceivablesPortfolioSegmentTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FinancingReceivableCollectivelyEvaluatedForImpairment",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2418410 - Disclosure - Loans - Recorded Investments in Loans (Details)",
     "role": "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails",
     "shortName": "Loans - Recorded Investments in Loans (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "inbk:AllowanceForCreditLossesOnFinancingReceivablesPortfolioSegmentTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FinancingReceivableCollectivelyEvaluatedForImpairment",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R48": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "inbk:AllowanceForCreditLossesOnFinancingReceivablesPortfolioSegmentTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LoansAndLeasesReceivableGrossCarryingAmount",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2419411 - Disclosure - Loans - Nonaccrual Loans (Details)",
     "role": "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
     "shortName": "Loans - Nonaccrual Loans (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FinancingReceivableCreditQualityIndicatorsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i9892f0ba59004129825bc077245b7717_I20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:LoansAndLeasesReceivableGrossCarryingAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R49": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "inbk:AllowanceForCreditLossesOnFinancingReceivablesPortfolioSegmentTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LoansAndLeasesReceivableGrossCarryingAmount",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2420412 - Disclosure - Loans Loans - Internal Credit Assessment (Details)",
     "role": "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
     "shortName": "Loans Loans - Internal Credit Assessment (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FinancingReceivableCreditQualityIndicatorsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i09b1b97485c148bc9514df8036c505d1_I20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:LoansAndLeasesReceivableGrossCarryingAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R5": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CompensationAndEmployeeBenefitPlansTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "document",
     "isDefault": "false",
     "longName": "0106110 - Document - Benefit Plans",
     "role": "http://www.firstib.com/role/BenefitPlans",
     "shortName": "Benefit Plans",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CompensationAndEmployeeBenefitPlansTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R50": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:PastDueFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FinancingReceivableRecordedInvestmentPastDue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2421413 - Disclosure - Loans - Loan Portfolio Aging (Details)",
     "role": "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
     "shortName": "Loans - Loan Portfolio Aging (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:PastDueFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FinancingReceivableRecordedInvestmentPastDue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R51": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ImpairedFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2422414 - Disclosure - Loans - Impaired Loans (Details)",
     "role": "http://www.firstib.com/role/LoansImpairedLoansDetails",
     "shortName": "Loans - Impaired Loans (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ImpairedFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i1bf2ee08a7e341ce9bcff14574c35b42_I20191231",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R52": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:PropertyPlantAndEquipmentTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2424415 - Disclosure - - Summary (Details)",
     "role": "http://www.firstib.com/role/SummaryDetails",
     "shortName": "- Summary (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:PropertyPlantAndEquipmentTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R53": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i383f695241624ca0afbe73a4e7b247cf_I20181231",
      "decimals": "1",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AreaOfLand",
      "reportCount": 1,
      "unique": true,
      "unitRef": "acre",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2425416 - Disclosure - Premises and Equipment - Narrative (Details)",
     "role": "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails",
     "shortName": "Premises and Equipment - Narrative (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i383f695241624ca0afbe73a4e7b247cf_I20181231",
      "decimals": "1",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AreaOfLand",
      "reportCount": 1,
      "unique": true,
      "unitRef": "acre",
      "xsiNil": "false"
     }
    },
    "R54": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "inbk:LesseeOperatingLeaseNumberOfLeases",
      "reportCount": 1,
      "unitRef": "lease",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2428417 - Disclosure - Leases (Details)",
     "role": "http://www.firstib.com/role/LeasesDetails",
     "shortName": "Leases (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:LeaseCostTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:OperatingLeaseCost",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R55": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "ix:continuation",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OperatingLeaseRightOfUseAsset",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2429418 - Disclosure - Leases - Balance Sheet Amounts (Details)",
     "role": "http://www.firstib.com/role/LeasesBalanceSheetAmountsDetails",
     "shortName": "Leases - Balance Sheet Amounts (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "ix:continuation",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OperatingLeaseRightOfUseAsset",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R56": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:LesseeOperatingLeaseLiabilityMaturityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2430419 - Disclosure - Leases - Maturity (Details)",
     "role": "http://www.firstib.com/role/LeasesMaturityDetails",
     "shortName": "Leases - Maturity (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:LesseeOperatingLeaseLiabilityMaturityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R57": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:Goodwill",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2431420 - Disclosure - Goodwill (Details)",
     "role": "http://www.firstib.com/role/GoodwillDetails",
     "shortName": "Goodwill (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R58": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfServicingAssetsAtFairValueTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i1bf2ee08a7e341ce9bcff14574c35b42_I20191231",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ServicingAssetAtFairValueAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2434421 - Disclosure - Servicing Asset (Details)",
     "role": "http://www.firstib.com/role/ServicingAssetDetails",
     "shortName": "Servicing Asset (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfServicingAssetsAtFairValueTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i1bf2ee08a7e341ce9bcff14574c35b42_I20191231",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ServicingAssetAtFairValueAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R59": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "ix:continuation",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "id519c2c2b013426e881304f3c87e446b_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NotesReceivableGross",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2435422 - Disclosure - Servicing Asset - Unpaid principal balance (Details)",
     "role": "http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails",
     "shortName": "Servicing Asset - Unpaid principal balance (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "ix:continuation",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "id519c2c2b013426e881304f3c87e446b_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:NotesReceivableGross",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R6": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "document",
     "isDefault": "false",
     "longName": "0107114 - Document - Derivative Financial Instruments",
     "role": "http://www.firstib.com/role/DerivativeFinancialInstruments",
     "shortName": "Derivative Financial Instruments",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R60": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfServicingAssetsAtFairValueTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ServicingAssetAtFairValueChangesInFairValueResultingFromChangesInValuationInputsOrChangesInAssumptions",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2436423 - Disclosure - Servicing Asset - Narrative (Details)",
     "role": "http://www.firstib.com/role/ServicingAssetNarrativeDetails",
     "shortName": "Servicing Asset - Narrative (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i860c6a7f651b483987860289a7dea5bb_D20200401-20200630",
      "decimals": "-5",
      "lang": "en-US",
      "name": "us-gaap:ServicingAssetAtFairValueChangesInFairValueResultingFromChangesInValuationInputsOrChangesInAssumptions",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R61": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i4efca494811945e880b4ab4cd5bebe55_I20151020",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DebtInstrumentFaceAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2438424 - Disclosure - Subordinated Debt (Details Textual)",
     "role": "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
     "shortName": "Subordinated Debt (Details Textual)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i4efca494811945e880b4ab4cd5bebe55_I20151020",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DebtInstrumentFaceAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R62": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "us-gaap:ScheduleOfSubordinatedBorrowingTextBlock",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i25ffecf274aa478caaae19e6a6b5a30a_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LongTermDebt",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2439425 - Disclosure - Subordinated Debt - Schedule of Subordinated Debt (Details)",
     "role": "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails",
     "shortName": "Subordinated Debt - Schedule of Subordinated Debt (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "us-gaap:ScheduleOfSubordinatedBorrowingTextBlock",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i25ffecf274aa478caaae19e6a6b5a30a_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LongTermDebt",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R63": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:NonvestedRestrictedStockSharesActivityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i355faf6cf5274b1ba8c38868360ffb04_I20191231",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2441426 - Disclosure - Benefit Plans - Activity (Details)",
     "role": "http://www.firstib.com/role/BenefitPlansActivityDetails",
     "shortName": "Benefit Plans - Activity (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:NonvestedRestrictedStockSharesActivityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i355faf6cf5274b1ba8c38868360ffb04_I20191231",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     }
    },
    "R64": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "inbk:ScheduleOfDeferredStockOptionPlanTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i1bf2ee08a7e341ce9bcff14574c35b42_I20191231",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "inbk:DeferredStockRelatedToDirectorsDeferredStockPlanOutstandingNumber",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2442427 - Disclosure - Benefit Plans - Deferred Stock Rights (Details)",
     "role": "http://www.firstib.com/role/BenefitPlansDeferredStockRightsDetails",
     "shortName": "Benefit Plans - Deferred Stock Rights (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "inbk:ScheduleOfDeferredStockOptionPlanTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i1bf2ee08a7e341ce9bcff14574c35b42_I20191231",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "inbk:DeferredStockRelatedToDirectorsDeferredStockPlanOutstandingNumber",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     }
    },
    "R65": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2443428 - Disclosure - Benefit Plans (Details Textual)",
     "role": "http://www.firstib.com/role/BenefitPlansDetailsTextual",
     "shortName": "Benefit Plans (Details Textual)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i5454ca49c40e4485a7383b61a159d544_D20200101-20200630",
      "decimals": null,
      "lang": "en-US",
      "name": "us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R66": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ContractualObligation",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2445429 - Disclosure - Commitments and Credit Risk (Details)",
     "role": "http://www.firstib.com/role/CommitmentsandCreditRiskDetails",
     "shortName": "Commitments and Credit Risk (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ContractualObligation",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R67": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AvailableForSaleSecuritiesDebtSecurities",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2448430 - Disclosure - Fair Value of Financial Instruments - Fair Value Hierarchy (Details)",
     "role": "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
     "shortName": "Fair Value of Financial Instruments - Fair Value Hierarchy (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueAssetsMeasuredOnRecurringBasisTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie75d42f5726442318a6d66274af7e360_I20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:LoansHeldForSaleFairValueDisclosure",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R68": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "if509873e9b1a4817afbeed1cc593f18b_I20200331",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2449431 - Disclosure - Fair Value of Financial Instruments - Fair Value Roll Forward (Details)",
     "role": "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails",
     "shortName": "Fair Value of Financial Instruments - Fair Value Roll Forward (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "if509873e9b1a4817afbeed1cc593f18b_I20200331",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R69": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ImpairedFinancingReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2450432 - Disclosure - Fair Value of Financial Instruments - Quantative Information About Unobservable Inputs (Details)",
     "role": "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
     "shortName": "Fair Value of Financial Instruments - Quantative Information About Unobservable Inputs (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "if05c86d7242b4c45a959319a51402dd1_I20191231",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:OtherRealEstate",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R7": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CashAndDueFromBanks",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1001002 - Statement - Condensed Consolidated Balance Sheets",
     "role": "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
     "shortName": "Condensed Consolidated Balance Sheets",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CashAndDueFromBanks",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R70": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CashAndCashEquivalentsAtCarryingValue",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2451433 - Disclosure - Fair Value of Financial Instruments - Carrying Value and Estimated Fair Value (Details)",
     "role": "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
     "shortName": "Fair Value of Financial Instruments - Carrying Value and Estimated Fair Value (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueByBalanceSheetGroupingTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "iadd249e0216b464cb5c4b4ed07635a1a_I20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:CashAndCashEquivalentsAtCarryingValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R71": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PaymentsForOriginationAndPurchasesOfLoansHeldForSale",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2454434 - Disclosure - Mortgage Banking Activities (Details)",
     "role": "http://www.firstib.com/role/MortgageBankingActivitiesDetails",
     "shortName": "Mortgage Banking Activities (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfParticipatingMortgageLoansTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i7c6d088c020b4ddeb4fb21beba5c1819_D20200401-20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:GainLossOnSaleOfLoansAndLeases",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R72": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i8da7b0d0666141b6961b25f79506a9db_I20200630",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AvailableForSaleSecuritiesAmortizedCost",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2456435 - Disclosure - Derivative Financial Instruments - Carrying Amount and Adjustment (Details)",
     "role": "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
     "shortName": "Derivative Financial Instruments - Carrying Amount and Adjustment (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i8da7b0d0666141b6961b25f79506a9db_I20200630",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AvailableForSaleSecuritiesAmortizedCost",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R73": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DerivativeNotionalAmount",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2457436 - Disclosure - Derivative Financial Instruments - Interest Swap Derivatives (Details)",
     "role": "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
     "shortName": "Derivative Financial Instruments - Interest Swap Derivatives (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "inbk:ScheduleOfDerivativeInstrumentsOfFixedRateReceivablesTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i6560bec8449c43bfaff6b1d6812b485a_D20200101-20200331",
      "decimals": null,
      "lang": "en-US",
      "name": "us-gaap:DerivativeAverageRemainingMaturity1",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R74": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DerivativeAssetNotionalAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2458437 - Disclosure - Derivative Financial Instruments - Notional Amounts and Fair Value (Details)",
     "role": "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
     "shortName": "Derivative Financial Instruments - Notional Amounts and Fair Value (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0e53359a053343eb8a23d953dc3098e9_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DerivativeAssetNotionalAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R75": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "inbk:ScheduleOfDerivativeInstrumentsInStatementsOfIncomeFairValueTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie2852394af6a4289b354afa6a48315d3_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2459438 - Disclosure - Derivative Financial Instruments - Gain (Loss) Recognized (Details)",
     "role": "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
     "shortName": "Derivative Financial Instruments - Gain (Loss) Recognized (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "inbk:ScheduleOfDerivativeInstrumentsInStatementsOfIncomeFairValueTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie2852394af6a4289b354afa6a48315d3_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R76": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfCashFlowHedgesIncludedInAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ifc10460dd6d14bbfac7fd7c1a3424b77_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2460439 - Disclosure - Derivative Financial Instruments - Effect Of Derivatives on Income (Details)",
     "role": "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails",
     "shortName": "Derivative Financial Instruments - Effect Of Derivatives on Income (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfCashFlowHedgesIncludedInAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ifc10460dd6d14bbfac7fd7c1a3424b77_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R77": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i0a6b9589e2674cf69256f9ca0aaba7f4_I20200331",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquity",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2463440 - Disclosure - Accumulated Other Comprehensive Loss (Details)",
     "role": "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails",
     "shortName": "Accumulated Other Comprehensive Loss (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:OciBeforeReclassificationsBeforeTaxAttributableToParent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R8": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "ix:continuation",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "i1bf2ee08a7e341ce9bcff14574c35b42_I20191231",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:HeldToMaturitySecuritiesFairValue",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1002003 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)",
     "role": "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical",
     "shortName": "Condensed Consolidated Balance Sheets (Parenthetical)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": null
    },
    "R9": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:InterestAndFeeIncomeLoansAndLeases",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1003004 - Statement - Condensed Consolidated Statements of Income (Unaudited)",
     "role": "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
     "shortName": "Condensed Consolidated Statements of Income (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "inbk-20200630.htm",
      "contextRef": "ie4ab59231e49408a8fb4e6da9be0d84c_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:InterestAndFeeIncomeLoansAndLeases",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    }
   },
   "segmentCount": 106,
   "tag": {
    "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "gYearItemType"
    },
    "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.firstib.com/role/Cover"
     ],
     "xbrltype": "dateItemType"
    },
    "dei_DocumentQuarterlyReport": {
     "auth_ref": [
      "r593"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_DocumentTransitionReport": {
     "auth_ref": [
      "r594"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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 Line One",
        "terseLabel": "Entity Address, Address Line One"
       }
      }
     },
     "localname": "EntityAddressAddressLine1",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "stateOrProvinceItemType"
    },
    "dei_EntityCentralIndexKey": {
     "auth_ref": [
      "r595"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityEmergingGrowthCompany": {
     "auth_ref": [
      "r595"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "fileNumberItemType"
    },
    "dei_EntityFilerCategory": {
     "auth_ref": [
      "r595"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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 or Country Code",
        "terseLabel": "Entity Incorporation, State or Country Code"
       }
      }
     },
     "localname": "EntityIncorporationStateCountryCode",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.firstib.com/role/Cover"
     ],
     "xbrltype": "edgarStateCountryItemType"
    },
    "dei_EntityInteractiveDataCurrent": {
     "auth_ref": [
      "r596"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityRegistrantName": {
     "auth_ref": [
      "r595"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityShellCompany": {
     "auth_ref": [
      "r595"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntitySmallBusiness": {
     "auth_ref": [
      "r595"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntityTaxIdentificationNumber": {
     "auth_ref": [
      "r595"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "employerIdItemType"
    },
    "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.firstib.com/role/Cover"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_Security12bTitle": {
     "auth_ref": [
      "r591"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Title of a 12(b) registered security.",
        "label": "Title of 12(b) Security",
        "terseLabel": "Title of 12(b) Security"
       }
      }
     },
     "localname": "Security12bTitle",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://www.firstib.com/role/Cover"
     ],
     "xbrltype": "securityTitleItemType"
    },
    "dei_SecurityExchangeName": {
     "auth_ref": [
      "r592"
     ],
     "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.firstib.com/role/Cover"
     ],
     "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.firstib.com/role/Cover"
     ],
     "xbrltype": "tradingSymbolItemType"
    },
    "inbk_A1MonthLIBORMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "1 Month LIBOR [Member]",
        "label": "1 Month LIBOR [Member]",
        "terseLabel": "1-month LIBOR"
       }
      }
     },
     "localname": "A1MonthLIBORMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_A3MonthLIBORMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "3 Month LIBOR [Member]",
        "label": "3 Month LIBOR [Member]",
        "terseLabel": "3-month LIBOR"
       }
      }
     },
     "localname": "A3MonthLIBORMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_A6.4375PercentNotesDue2025Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "6.4375 Percent Notes Due 2025",
        "label": "6.4375 Percent Notes Due 2025 [Member]",
        "terseLabel": "2025 Note"
       }
      }
     },
     "localname": "A6.4375PercentNotesDue2025Member",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_A60FixedToFloatingSubordinatedNotesDue2026Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "6.0% Fixed To Floating Subordinated Notes Due 2026",
        "label": "6.0% Fixed To Floating Subordinated Notes Due 2026 [Member]",
        "terseLabel": "6.0% Fixed to Floating Subordinated Notes due 2026"
       }
      }
     },
     "localname": "A60FixedToFloatingSubordinatedNotesDue2026Member",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/Cover"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_A60FixedToFloatingSubordinatedNotesDue2029Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "6.0% Fixed To Floating Subordinated Notes Due 2029",
        "label": "6.0% Fixed To Floating Subordinated Notes Due 2029 [Member]",
        "terseLabel": "6.0% Fixed to Floating Subordinated Notes due 2029"
       }
      }
     },
     "localname": "A60FixedToFloatingSubordinatedNotesDue2029Member",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/Cover"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_A6PercentFixedToFloatingRateSubordinatedNotesDue2029Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "6 Percent Fixed To Floating Rate Subordinated Notes Due 2029 [Member]",
        "label": "6 Percent Fixed To Floating Rate Subordinated Notes Due 2029 [Member]",
        "terseLabel": "2029 Notes"
       }
      }
     },
     "localname": "A6PercentFixedToFloatingRateSubordinatedNotesDue2029Member",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_A6PercentNotesDue2021Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "6 Percent Notes Due 2021",
        "label": "6 Percent Notes Due 2021 [Member]",
        "terseLabel": "2026 Notes"
       }
      }
     },
     "localname": "A6PercentNotesDue2021Member",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_AllowanceForCreditLossesOnFinancingReceivablesPortfolioSegmentTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of financing receivables (examples of financing receivables include loans, trade accounts receivable and notes receivable) and activity in the allowance for credit losses account.",
        "label": "Allowance For Credit Losses On Financing Receivables Portfolio Segment [Table Text Block]",
        "terseLabel": "Allowance For Credit Losses On Financing Receivables Portfolio Segment"
       }
      }
     },
     "localname": "AllowanceForCreditLossesOnFinancingReceivablesPortfolioSegmentTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_AllowancesForLoansAndLeaseLossProvisionForLossNetAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Allowances for loans and lease loss provision for loss net [Abstract]",
        "verboseLabel": "Allowance for loan losses:"
       }
      }
     },
     "localname": "AllowancesForLoansAndLeaseLossProvisionForLossNetAbstract",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "inbk_AssetAcquisitionAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Asset Acquisition [Axis]",
        "label": "Asset Acquisition [Axis]",
        "terseLabel": "Asset Acquisition [Axis]"
       }
      }
     },
     "localname": "AssetAcquisitionAxis",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "inbk_AssetAcquisitionDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "[Domain] for Asset Acquisition [Axis]",
        "label": "Asset Acquisition [Domain]",
        "terseLabel": "Asset Acquisition [Domain]"
       }
      }
     },
     "localname": "AssetAcquisitionDomain",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueInPercentage": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position in percentage.",
        "label": "Available For Sale Securities Continuous Unrealized Loss Position Fair Value In Percentage",
        "terseLabel": "Continuous unrealized loss position, fair value (as a percent)"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueInPercentage",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetailsTextual"
     ],
     "xbrltype": "percentItemType"
    },
    "inbk_COVID19Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "COVID-19 [Member]",
        "label": "COVID-19 [Member]",
        "terseLabel": "COVID-19"
       }
      }
     },
     "localname": "COVID19Member",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_CarryingValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Carrying value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.",
        "label": "Carrying Value Liabilities Measured On Recurring Basis Subordinated Debt Obligations",
        "terseLabel": "Subordinated debt, Carrying Value"
       }
      }
     },
     "localname": "CarryingValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_CashDividendsDeclaredNotPaid": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Common cash dividends declared but unpaid as of the balance sheet date.",
        "label": "Cash dividends declared, not paid",
        "terseLabel": "Cash dividends declared, paid in subsequent period"
       }
      }
     },
     "localname": "CashDividendsDeclaredNotPaid",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_CommonStockSharesReservedForFutureGrants": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Represents the total number of common stock shares which can be grants under the plan.",
        "label": "Common Stock Shares Reserved For Future Grants",
        "terseLabel": "Common stock shares reserved for future grants (in shares)"
       }
      }
     },
     "localname": "CommonStockSharesReservedForFutureGrants",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "sharesItemType"
    },
    "inbk_DebtSecuritiesAvailableForSaleNumberOfSecuritiesTransferredToHeldForSale": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt Securities, Available For Sale, Number Of Securities Transferred To Held For Sale",
        "label": "Debt Securities, Available For Sale, Number Of Securities Transferred To Held For Sale",
        "terseLabel": "Number of available for sale securities transferred to held for sale"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleNumberOfSecuritiesTransferredToHeldForSale",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetailsTextual"
     ],
     "xbrltype": "integerItemType"
    },
    "inbk_DebtSecuritiesAvailableForSaleTransferToHeldToMaturityGainLoss": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt Securities, Available-For-sale, Transfer To Held To Maturity, Gain (Loss)",
        "label": "Debt Securities, Available-For-sale, Transfer To Held To Maturity, Gain (Loss)",
        "terseLabel": "Unrealized holding gain, net of tax, retained in accumulated other comprehensive income"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleTransferToHeldToMaturityGainLoss",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetailsTextual"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_DebtSecuritiesAvailableForSaleTransferredToHeldToMaturity": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt Securities, Available For Sale, Transferred To Held To Maturity",
        "label": "Debt Securities, Available For Sale, Transferred To Held To Maturity",
        "terseLabel": "Available for sale securities transferred to held to maturity"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleTransferredToHeldToMaturity",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetailsTextual"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_DeferredStockRelatedToDirectorsDeferredStockPlanExercisedInPeriod": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "It represents the deferred stock rights exercised during the period related to deferred stock plan.",
        "label": "Deferred Stock Related To Directors Deferred Stock Plan Exercised In Period",
        "negatedLabel": "Exercised"
       }
      }
     },
     "localname": "DeferredStockRelatedToDirectorsDeferredStockPlanExercisedInPeriod",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDeferredStockRightsDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "inbk_DeferredStockRelatedToDirectorsDeferredStockPlanGrantedInPeriod": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "It represents the deferred stock rights granted to directors during the period related to deferred stock plan.",
        "label": "Deferred Stock Related To Directors Deferred Stock Plan Granted In Period",
        "terseLabel": "Granted"
       }
      }
     },
     "localname": "DeferredStockRelatedToDirectorsDeferredStockPlanGrantedInPeriod",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDeferredStockRightsDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "inbk_DeferredStockRelatedToDirectorsDeferredStockPlanOutstandingNumber": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "It represents the outstanding number of deferred stock rights related to directors deferred stock plan.",
        "label": "Deferred Stock Related To Directors Deferred Stock Plan Outstanding Number",
        "periodEndLabel": "Outstanding, end of period",
        "periodStartLabel": "Outstanding, beginning of period"
       }
      }
     },
     "localname": "DeferredStockRelatedToDirectorsDeferredStockPlanOutstandingNumber",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDeferredStockRightsDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "inbk_DeferredStockUnitsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Deferred Stock Units [Member]",
        "label": "Deferred Stock Units [Member]",
        "terseLabel": "Deferred Stock Units"
       }
      }
     },
     "localname": "DeferredStockUnitsMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails",
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_DerivativeFinancialInstrumentFairValueDisclosure": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of derivative financial instrument.",
        "label": "Derivative Financial Instrument, Fair Value Disclosure",
        "verboseLabel": "IRLCs Fair Value"
       }
      }
     },
     "localname": "DerivativeFinancialInstrumentFairValueDisclosure",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_FederalHomeLoanBankStockAtFairValue": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This element represents the portion of the balance sheet assertion valued at fair value by the entity 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. This item represents an amount a bank borrows from the Federal Home Loan Bank stock as of the balance sheet date.",
        "label": "Federal Home Loan Bank Stock At Fair Value",
        "terseLabel": "FHLB stock, Fair Value"
       }
      }
     },
     "localname": "FederalHomeLoanBankStockAtFairValue",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_FishersTownHallBuildingCorporationMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fishers Town Hall Building Corporation [Member]",
        "label": "Fishers Town Hall Building Corporation [Member]",
        "terseLabel": "Fishers Town Hall Building Corporation"
       }
      }
     },
     "localname": "FishersTownHallBuildingCorporationMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_GainLossOnDerivatives": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 8.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Gain or (loss) recognized in the income statement related to the fair value adjustment of derivatives.",
        "label": "Gain Loss On Derivatives",
        "negatedTerseLabel": "Loss (gain) on derivatives"
       }
      }
     },
     "localname": "GainLossOnDerivatives",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_HealthcareFinanceMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Healthcare Finance",
        "label": "Healthcare Finance [Member]",
        "terseLabel": "Healthcare finance"
       }
      }
     },
     "localname": "HealthcareFinanceMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_HeldtoMaturityContinuousUnrealizedLossPositionFairValueTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Held to Maturity, Continuous Unrealized Loss Position, Fair Value [Table Text Block]",
        "label": "Held to Maturity, Continuous Unrealized Loss Position, Fair Value [Table Text Block]",
        "terseLabel": "Held to Maturity, Continuous Unrealized Loss Position, Fair Value"
       }
      }
     },
     "localname": "HeldtoMaturityContinuousUnrealizedLossPositionFairValueTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_ImpairedFinancingReceivableLoansWithNoSpecificRelatedAllowance": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_ImpairedFinancingReceivableRelatedAllowance",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of allowance for credit losses related to recorded investment not with a specific valuation allowance.",
        "label": "Impaired Financing Receivable Loans With No Specific Related Allowance",
        "terseLabel": "Loans without a specific valuation allowance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableLoansWithNoSpecificRelatedAllowance",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_ImpairedFinancingReceivableLoansWithSpecificRelatedAllowance": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_ImpairedFinancingReceivableRelatedAllowance",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of allowance for credit losses related to recorded investment with specific valuation allowance.",
        "label": "Impaired Financing Receivable Loans With Specific Related Allowance",
        "terseLabel": "Loans with a specific valuation allowance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableLoansWithSpecificRelatedAllowance",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_ImpairedLoansMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Impaired Loans [Member]",
        "label": "Impaired Loans [Member]",
        "terseLabel": "Impaired Loans"
       }
      }
     },
     "localname": "ImpairedLoansMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_IncreaseDecreaseInCashSurrenderValueOfLifeInsurance": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 16.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Represents the amount of increase(decrease) in cash surrender value of bank-owned life insurance.",
        "label": "Increase Decrease In Cash Surrender Value Of Life Insurance",
        "verboseLabel": "Increase in cash surrender value of bank-owned life insurance"
       }
      }
     },
     "localname": "IncreaseDecreaseInCashSurrenderValueOfLifeInsurance",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_IncreaseDecreaseInServicingAssets": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 10.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Increase (Decrease) In Servicing Assets",
        "label": "Increase (Decrease) In Servicing Assets",
        "negatedTerseLabel": "Net change in servicing asset"
       }
      }
     },
     "localname": "IncreaseDecreaseInServicingAssets",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_InterestIncomeNetMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Interest Income, Net [Member]",
        "label": "Interest Income, Net [Member]",
        "terseLabel": "Net interest income"
       }
      }
     },
     "localname": "InterestIncomeNetMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_InterestPayableAtFairValue": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. This item represents the amount of accrued interest payable as of the balance sheet date.",
        "label": "Interest Payable At Fair Value",
        "terseLabel": "Accrued interest payable, Fair Value"
       }
      }
     },
     "localname": "InterestPayableAtFairValue",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_InterestReceivableAtFairValue": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. This item represents interest receivable as presented on the statement of financial position which are due the Company as of the balance sheet date.",
        "label": "Interest Receivable At Fair Value",
        "terseLabel": "Accrued interest receivable, Fair Value"
       }
      }
     },
     "localname": "InterestReceivableAtFairValue",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_IrlcLoanClosingRates": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "It represents the IRLC on percentage range of fair value assets and Liabilities.",
        "label": "IRLC - Loan Closing Rates",
        "terseLabel": "IRLC - Loan closing rates"
       }
      }
     },
     "localname": "IrlcLoanClosingRates",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "inbk_LandAcquisitionMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Land Acquisition [Member]",
        "label": "Land Acquisition [Member]",
        "terseLabel": "Land Acquisition"
       }
      }
     },
     "localname": "LandAcquisitionMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_LesseeOperatingLeaseNumberOfLeases": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Lessee, Operating Lease, Number Of Leases",
        "label": "Lessee, Operating Lease, Number Of Leases",
        "terseLabel": "Number of leases"
       }
      }
     },
     "localname": "LesseeOperatingLeaseNumberOfLeases",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LeasesDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "inbk_LesseeOperatingLeaseRemainingTermOfContract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Lessee, Operating Lease, Remaining Term Of Contract",
        "label": "Lessee, Operating Lease, Remaining Term Of Contract",
        "terseLabel": "Remaining term of contract"
       }
      }
     },
     "localname": "LesseeOperatingLeaseRemainingTermOfContract",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LeasesDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "inbk_LesseeSupplementalBalanceSheetTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Lessee, Supplemental Balance Sheet [Table Text Block]",
        "label": "Lessee, Supplemental Balance Sheet [Table Text Block]",
        "terseLabel": "Lessee, Supplemental Balance Sheet"
       }
      }
     },
     "localname": "LesseeSupplementalBalanceSheetTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LeasesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_LesseeSupplementalCashFlowTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Lessee, Supplemental Cash Flow [Table Text Block]",
        "label": "Lessee, Supplemental Cash Flow [Table Text Block]",
        "terseLabel": "Lessee, Supplemental Cash Flow"
       }
      }
     },
     "localname": "LesseeSupplementalCashFlowTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LeasesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_LoanLifeTerm": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loan Life Term",
        "label": "Loan Life Term",
        "terseLabel": "Loan life term"
       }
      }
     },
     "localname": "LoanLifeTerm",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "inbk_LoanServicingAssetRevaluationMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loan Servicing Asset Revaluation [Member]",
        "label": "Loan Servicing Asset Revaluation [Member]",
        "terseLabel": "Loan servicing asset revaluation"
       }
      }
     },
     "localname": "LoanServicingAssetRevaluationMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_LoanServicingMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loan Servicing [Member]",
        "label": "Loan Servicing [Member]",
        "terseLabel": "Loan servicing revenue",
        "verboseLabel": "Loan servicing"
       }
      }
     },
     "localname": "LoanServicingMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/ServicingAssetNarrativeDetails",
      "http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_LoansAndLeasesReceivableReclassifiedGross": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loans And Leases Receivable, Reclassified, Gross",
        "label": "Loans And Leases Receivable, Reclassified, Gross",
        "terseLabel": "Loans reclassified"
       }
      }
     },
     "localname": "LoansAndLeasesReceivableReclassifiedGross",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_LoansHeldForSaleMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Loans Held For Sale [Member]",
        "terseLabel": "Loans held-for-sale (mandatory pricing agreements)"
       }
      }
     },
     "localname": "LoansHeldForSaleMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_MeasurementInputDiscountForTypeOfPropertyAndCurrentMarketConditionsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement Input, Discount For Type Of Property And Current Market Conditions [Member]",
        "label": "Measurement Input, Discount For Type Of Property And Current Market Conditions [Member]",
        "terseLabel": "Discount for type of property and current market conditions"
       }
      }
     },
     "localname": "MeasurementInputDiscountForTypeOfPropertyAndCurrentMarketConditionsMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_MeasurementInputLoanClosingRatesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement Input, Loan Closing Rates [Member]",
        "label": "Measurement Input, Loan Closing Rates [Member]",
        "terseLabel": "Loan closing rates"
       }
      }
     },
     "localname": "MeasurementInputLoanClosingRatesMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_MortgageLoansInProcessOfForeclosureNumberOfLoans": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Mortgage Loans In Process Of Foreclosure, Number Of Loans",
        "label": "Mortgage Loans In Process Of Foreclosure, Number Of Loans",
        "terseLabel": "Mortgage loans in process of foreclosure, number of loans"
       }
      }
     },
     "localname": "MortgageLoansInProcessOfForeclosureNumberOfLoans",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "inbk_NumberOfAdditionalParcelsOfLandTransferred": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number Of Additional Parcels Of Land Transferred",
        "label": "Number Of Additional Parcels Of Land Transferred",
        "terseLabel": "Number of additional parcels of land transferred"
       }
      }
     },
     "localname": "NumberOfAdditionalParcelsOfLandTransferred",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "inbk_NumberOfWhollyOwnedSubsidiaries": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number Of Wholly Owned Subsidiaries",
        "label": "Number Of Wholly Owned Subsidiaries",
        "terseLabel": "Number of wholly-owned subsidiaries"
       }
      }
     },
     "localname": "NumberOfWhollyOwnedSubsidiaries",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/BasisofPresentationDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "inbk_OperatingLeaseLiabilityInitialRecognition": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Operating Lease, Liability, Initial Recognition",
        "label": "Operating Lease, Liability, Initial Recognition",
        "terseLabel": "Initial recognition of operating lease liabilities"
       }
      }
     },
     "localname": "OperatingLeaseLiabilityInitialRecognition",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_OperatingLeaseLiabilityNet": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/LeasesMaturityDetails_1": {
       "order": 2.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Operating Lease, Liability, Net",
        "label": "Operating Lease, Liability, Net",
        "terseLabel": "Operating lease liabilities"
       }
      }
     },
     "localname": "OperatingLeaseLiabilityNet",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LeasesMaturityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_OperatingLeaseRightOfUseAssetAmortization": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 11.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Operating Lease, Right Of Use Asset, Amortization",
        "label": "Operating Lease, Right Of Use Asset, Amortization",
        "terseLabel": "Amortization of operating lease right-of-use assets"
       }
      }
     },
     "localname": "OperatingLeaseRightOfUseAssetAmortization",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_OtherBorrowedFundsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other Borrowed Funds [Member]",
        "label": "Other Borrowed Funds [Member]",
        "terseLabel": "Other borrowed funds"
       }
      }
     },
     "localname": "OtherBorrowedFundsMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_OtherCommitmentNotIncurred": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other Commitment, Not Incurred",
        "label": "Other Commitment, Not Incurred",
        "terseLabel": "Construction related contract commitment, not yet incurred"
       }
      }
     },
     "localname": "OtherCommitmentNotIncurred",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRiskDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_OtherCommitmentTerm": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other Commitment, Term",
        "label": "Other Commitment, Term",
        "terseLabel": "Construction related contract commitment, term"
       }
      }
     },
     "localname": "OtherCommitmentTerm",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRiskDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "inbk_OtherCommitmentsCapitalCommittedToSmallBusinessInvestmentCompanyFund": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other Commitments, Capital Committed To Small Business Investment Company Fund",
        "label": "Other Commitments, Capital Committed To Small Business Investment Company Fund",
        "terseLabel": "Capital committed to Small Business Investment Company fund, not contributed"
       }
      }
     },
     "localname": "OtherCommitmentsCapitalCommittedToSmallBusinessInvestmentCompanyFund",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRiskDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_OtherComprehensiveIncomeLossAvailableforsaleSecuritiesNetUnrealizedHoldingGainsLossesOtherThanTemporaryImpairmentsRecognizedinIncome": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossBeforeTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other Comprehensive Income (Loss), Available-for-sale Securities, Net Unrealized Holding Gains (Losses), Other Than Temporary Impairments Recognized in Income",
        "label": "Other Comprehensive Income (Loss), Available-for-sale Securities, Net Unrealized Holding Gains (Losses), Other Than Temporary Impairments Recognized in Income",
        "terseLabel": "Net unrealized holding losses on cash flow hedging derivatives recorded within other comprehensive (loss) income before tax"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossAvailableforsaleSecuritiesNetUnrealizedHoldingGainsLossesOtherThanTemporaryImpairmentsRecognizedinIncome",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_OtherConsumerLoansMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other Consumer Loans [Member]",
        "label": "Other Consumer Loans [Member]",
        "terseLabel": "Other consumer"
       }
      }
     },
     "localname": "OtherConsumerLoansMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_OtherRealEstateOwnedDiscountRate": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other Real Estate Owned, Discount Rate",
        "label": "Other Real Estate Owned, Discount Rate",
        "terseLabel": "Other real estate owned, discount rate"
       }
      }
     },
     "localname": "OtherRealEstateOwnedDiscountRate",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "inbk_OtherRealEstateOwnedMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other Real Estate Owned [Member]",
        "label": "Other Real Estate Owned [Member]",
        "terseLabel": "Other Real Estate Owned"
       }
      }
     },
     "localname": "OtherRealEstateOwnedMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_OtherSecuritiesUnobservableInputs": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "It represents the other securities fair value assets and Liabilities unobservable inputs description.",
        "label": "Other Securities Unobservable Inputs",
        "terseLabel": "Other securities Unobservable Inputs"
       }
      }
     },
     "localname": "OtherSecuritiesUnobservableInputs",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "inbk_OtherSecuritiesValuationTechnique": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "It represents the other securities On fair value assets and Liabilities Valuation Technique.",
        "label": "Other Securities Valuation Technique",
        "terseLabel": "Other securities Valuation Technique"
       }
      }
     },
     "localname": "OtherSecuritiesValuationTechnique",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "inbk_OwnerOccupiedCommercialRealEstateMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Owner Occupied Commercial Real Estate [Member]",
        "label": "Owner Occupied Commercial Real Estate [Member]",
        "terseLabel": "Owner-occupied commercial real estate"
       }
      }
     },
     "localname": "OwnerOccupiedCommercialRealEstateMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_Plan2013Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Plan 2013 [Member]",
        "terseLabel": "Plan 2013"
       }
      }
     },
     "localname": "Plan2013Member",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_ProceedsFromPurchasePriceReimbursement": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Proceeds From Purchase Price Reimbursement",
        "label": "Proceeds From Purchase Price Reimbursement",
        "terseLabel": "Proceeds from purchase price reimbursement"
       }
      }
     },
     "localname": "ProceedsFromPurchasePriceReimbursement",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_PublicFinanceMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Public Finance [Member]",
        "label": "Public Finance [Member]",
        "terseLabel": "Public finance"
       }
      }
     },
     "localname": "PublicFinanceMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_RightOfUseLeasedAssetMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Right Of Use Leased Asset [Member]",
        "label": "Right Of Use Leased Asset [Member]",
        "terseLabel": "Right of use leased asset"
       }
      }
     },
     "localname": "RightOfUseLeasedAssetMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_SBAGuaranteedLoansMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "SBA Guaranteed Loans [Member]",
        "label": "SBA Guaranteed Loans [Member]",
        "terseLabel": "SBA guaranteed loans"
       }
      }
     },
     "localname": "SBAGuaranteedLoansMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_ScheduleOfDeferredStockOptionPlanTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the description of the plan, analysis of deferred stock rights and common stock related to directors deferred stock plan.",
        "label": "Schedule Of Deferred Stock Option Plan [Table Text Block]",
        "terseLabel": "Schedule Of Deferred Stock Option Plan"
       }
      }
     },
     "localname": "ScheduleOfDeferredStockOptionPlanTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_ScheduleOfDerivativeInstrumentsCumulativeBasisAdjustmentsTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule Of Derivative Instruments, Cumulative Basis Adjustments [Table Text Block]",
        "label": "Schedule Of Derivative Instruments, Cumulative Basis Adjustments [Table Text Block]",
        "terseLabel": "Schedule Of Derivative Instruments, Cumulative Basis Adjustments"
       }
      }
     },
     "localname": "ScheduleOfDerivativeInstrumentsCumulativeBasisAdjustmentsTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_ScheduleOfDerivativeInstrumentsInStatementsOfIncomeFairValueTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the location and fair value amounts of derivative instruments (and nonderivative instruments that are designated and qualify as hedging instruments) reported in the statement of income.",
        "label": "Schedule Of Derivative Instruments In Statements Of Income Fair Value [Table Text Block]",
        "terseLabel": "Schedule of Derivative Instruments in Statements of Income Fair Value"
       }
      }
     },
     "localname": "ScheduleOfDerivativeInstrumentsInStatementsOfIncomeFairValueTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_ScheduleOfDerivativeInstrumentsOfFixedRateReceivablesTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule Of Derivative Instruments Of Fixed Rate Receivables [Table Text Block]",
        "label": "Schedule Of Derivative Instruments Of Fixed Rate Receivables [Table Text Block]",
        "terseLabel": "Schedule Of Derivative Instruments Of Fixed Rate Receivables"
       }
      }
     },
     "localname": "ScheduleOfDerivativeInstrumentsOfFixedRateReceivablesTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_ScheduleOfDerivativeInstrumentsOfVariableRateLiabilitiesTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule Of Derivative Instruments Of Variable Rate Liabilities [Table Text Block]",
        "label": "Schedule Of Derivative Instruments Of Variable Rate Liabilities [Table Text Block]",
        "terseLabel": "Schedule Of Derivative Instruments Of Variable Rate Liabilities"
       }
      }
     },
     "localname": "ScheduleOfDerivativeInstrumentsOfVariableRateLiabilitiesTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_ScheduleOfHeldToMaturitySecuritiesReconciliationTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule Of Held-To-Maturity Securities Reconciliation",
        "label": "Schedule Of Held-To-Maturity Securities Reconciliation [Table Text Block]",
        "terseLabel": "Schedule Of Held-To-Maturity Securities Reconciliation"
       }
      }
     },
     "localname": "ScheduleOfHeldToMaturitySecuritiesReconciliationTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_ScheduleOfImpairedLoansIncludingValuationAllowanceFairValueUnobservableInputsReconciliationTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule Of Impaired Loans, Including Valuation Allowance, Fair Value, Unobservable Inputs Reconciliation [Table Text Block]",
        "label": "Schedule Of Impaired Loans, Including Valuation Allowance, Fair Value, Unobservable Inputs Reconciliation [Table Text Block]",
        "terseLabel": "Schedule Of Impaired Loans, Including Valuation Allowance, Fair Value, Unobservable Inputs Reconciliation"
       }
      }
     },
     "localname": "ScheduleOfImpairedLoansIncludingValuationAllowanceFairValueUnobservableInputsReconciliationTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_ScheduleOfUnpaidPrincipalBalancesOfLoansServicedForOthersTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule Of Unpaid Principal Balances Of Loans Serviced For Others [Table Text Block]",
        "label": "Schedule Of Unpaid Principal Balances Of Loans Serviced For Others [Table Text Block]",
        "terseLabel": "Schedule Of Unpaid Principal Balances Of Loans Serviced For Others"
       }
      }
     },
     "localname": "ScheduleOfUnpaidPrincipalBalancesOfLoansServicedForOthersTableTextBlock",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/ServicingAssetTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "inbk_SecuritiesContinuousUnrealizedLossPositionFairValue": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Securities, Continuous Unrealized Loss Position, Fair Value",
        "label": "Securities, Continuous Unrealized Loss Position, Fair Value",
        "terseLabel": "Continuous unrealized loss position, fair value"
       }
      }
     },
     "localname": "SecuritiesContinuousUnrealizedLossPositionFairValue",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetailsTextual"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_SecuritiesNonTaxableMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Securities, Non Taxable [Member]",
        "label": "Securities, Non Taxable [Member]",
        "terseLabel": "Securities - non-taxable"
       }
      }
     },
     "localname": "SecuritiesNonTaxableMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_SecuritiesPurchasedDuringPeriodSettledInSubsequentPeriod": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Securities Purchased During Period, Settled In Subsequent Period",
        "label": "Securities Purchased During Period, Settled In Subsequent Period",
        "terseLabel": "Securities purchased during the period, settled in subsequent period"
       }
      }
     },
     "localname": "SecuritiesPurchasedDuringPeriodSettledInSubsequentPeriod",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_SecuritiesTaxableMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Securities, Taxable [Member]",
        "label": "Securities, Taxable [Member]",
        "terseLabel": "Securities - taxable"
       }
      }
     },
     "localname": "SecuritiesTaxableMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_ServicingAssetMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Servicing Asset [Member]",
        "label": "Servicing Asset [Member]",
        "terseLabel": "Servicing asset"
       }
      }
     },
     "localname": "ServicingAssetMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_SettlementOfDerivative": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 13.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Settlement Of Derivative",
        "label": "Settlement Of Derivative",
        "negatedTerseLabel": "Settlement of derivatives"
       }
      }
     },
     "localname": "SettlementOfDerivative",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_SharebasedCompensationArrangementbySharebasePaymentAwardPercentageofAnnualRetainerReceivedinCommonStockorDeferredStockRights": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Share-based Compensation Arrangement by Share-base Payment Award, Percentage of Annual Retainer Received in Common Stock or Deferred Stock Rights",
        "label": "Share-based Compensation Arrangement by Share-base Payment Award, Percentage of Annual Retainer Received in Common Stock or Deferred Stock Rights",
        "terseLabel": "Percentage of annual retainer received in either common stock or deferred stock rights"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementbySharebasePaymentAwardPercentageofAnnualRetainerReceivedinCommonStockorDeferredStockRights",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "percentItemType"
    },
    "inbk_SingleTenantLeaseMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Single Tenant Lease [Member]",
        "label": "Single Tenant Lease [Member]",
        "terseLabel": "Single tenant lease financing"
       }
      }
     },
     "localname": "SingleTenantLeaseMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_SmallBusinessLendingMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Small Business Lending [Member]",
        "label": "Small Business Lending [Member]",
        "verboseLabel": "Small business lending"
       }
      }
     },
     "localname": "SmallBusinessLendingMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_ThirdPartiesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Third Parties [Member]",
        "label": "Third Parties [Member]",
        "terseLabel": "Third Parties"
       }
      }
     },
     "localname": "ThirdPartiesMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_TransferOfEquityInvestmentsFromAvailableForSaleToOtherAssets": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Transfer Of Equity Investments From Available For Sale To Other Assets",
        "label": "Transfer Of Equity Investments From Available For Sale To Other Assets",
        "terseLabel": "Transfer of available-for-sale municipal securities to held-to-maturity municipal securities"
       }
      }
     },
     "localname": "TransferOfEquityInvestmentsFromAvailableForSaleToOtherAssets",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_UnrealizedGainLossOnLoansHeldForSale": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of gain (loss) recognized in the income statement for the fair value adjustment of loans held for sale.",
        "label": "Unrealized Gain Loss On Loans Held For Sale",
        "negatedTerseLabel": "Decrease (increase) in fair value of loans held-for-sale"
       }
      }
     },
     "localname": "UnrealizedGainLossOnLoansHeldForSale",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "inbk_ValuationTechniqueFairValueOfCollateralMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Valuation Technique, Fair Value Of Collateral [Member]",
        "label": "Valuation Technique, Fair Value Of Collateral [Member]",
        "terseLabel": "Fair value of collateral"
       }
      }
     },
     "localname": "ValuationTechniqueFairValueOfCollateralMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_VotingAndNonVotingCommonStockMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Voting and Non Voting Common Stock [Member]",
        "terseLabel": "Voting\u00a0and Nonvoting Common Stock"
       }
      }
     },
     "localname": "VotingAndNonVotingCommonStockMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "inbk_VotingCommonStockMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Voting Common Stock [Member]",
        "terseLabel": "Voting Common Stock"
       }
      }
     },
     "localname": "VotingCommonStockMember",
     "nsuri": "http://www.firstib.com/20200630",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_ConsolidatedEntitiesAxis": {
     "auth_ref": [
      "r357",
      "r358",
      "r361",
      "r362",
      "r590",
      "r597"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by consolidated entity or group of entities.",
        "label": "Consolidated Entities [Axis]",
        "terseLabel": "Consolidated Entities [Axis]"
       }
      }
     },
     "localname": "ConsolidatedEntitiesAxis",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_ConsolidatedEntitiesDomain": {
     "auth_ref": [
      "r357",
      "r358",
      "r361",
      "r362"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Entity or group of entities consolidated into reporting entity.",
        "label": "Consolidated Entities [Domain]",
        "terseLabel": "Consolidated Entities [Domain]"
       }
      }
     },
     "localname": "ConsolidatedEntitiesDomain",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_CounterpartyNameAxis": {
     "auth_ref": [
      "r33",
      "r95",
      "r599"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by name of counterparty. A counterparty is the other party that participates in a financial transaction. Examples include, but not limited to, the name of the financial institution.",
        "label": "Counterparty Name [Axis]",
        "terseLabel": "Counterparty Name [Axis]"
       }
      }
     },
     "localname": "CounterpartyNameAxis",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember": {
     "auth_ref": [
      "r103",
      "r114",
      "r232",
      "r337",
      "r338",
      "r339",
      "r346",
      "r347"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Increase (decrease) to financial statements for cumulative-effect adjustment in period of adoption of amendment to accounting standards.",
        "label": "Cumulative Effect, Period of Adoption, Adjustment [Member]",
        "terseLabel": "Cumulative Effect, Period of Adoption, Adjustment"
       }
      }
     },
     "localname": "CumulativeEffectPeriodOfAdoptionAdjustmentMember",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_CumulativeEffectPeriodOfAdoptionAxis": {
     "auth_ref": [
      "r103",
      "r114",
      "r232",
      "r337",
      "r338",
      "r339",
      "r346",
      "r347"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by cumulative-effect adjustment to financial statements in period of adoption of amendment to accounting standards.",
        "label": "Cumulative Effect, Period of Adoption [Axis]",
        "terseLabel": "Cumulative Effect, Period of Adoption [Axis]"
       }
      }
     },
     "localname": "CumulativeEffectPeriodOfAdoptionAxis",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_CumulativeEffectPeriodOfAdoptionDomain": {
     "auth_ref": [
      "r103",
      "r114",
      "r232",
      "r337",
      "r338",
      "r339",
      "r346",
      "r347"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Cumulative-effect adjustment to financial statements in period of adoption of amendment to accounting standards.",
        "label": "Cumulative Effect, Period of Adoption [Domain]",
        "terseLabel": "Cumulative Effect, Period of Adoption [Domain]"
       }
      }
     },
     "localname": "CumulativeEffectPeriodOfAdoptionDomain",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_DirectorMember": {
     "auth_ref": [
      "r165"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Person serving on board of directors.",
        "label": "Director [Member]",
        "terseLabel": "Director"
       }
      }
     },
     "localname": "DirectorMember",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_MaximumMember": {
     "auth_ref": [
      "r316",
      "r317",
      "r446",
      "r447",
      "r448",
      "r452",
      "r453",
      "r454",
      "r490",
      "r565",
      "r567"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Upper limit of the provided range.",
        "label": "Maximum [Member]",
        "terseLabel": "Maximum"
       }
      }
     },
     "localname": "MaximumMember",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
      "http://www.firstib.com/role/LeasesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_MinimumMember": {
     "auth_ref": [
      "r316",
      "r317",
      "r446",
      "r447",
      "r448",
      "r452",
      "r453",
      "r454",
      "r490",
      "r565",
      "r567"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Lower limit of the provided range.",
        "label": "Minimum [Member]",
        "terseLabel": "Minimum"
       }
      }
     },
     "localname": "MinimumMember",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
      "http://www.firstib.com/role/LeasesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_MortgageLoansOnRealEstateByLoanDisclosureTextBlock": {
     "auth_ref": [
      "r586",
      "r598"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for 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. Includes, but is not limited to, information for each mortgage loan receivable equaling or exceeding three percent of carrying amount of mortgage.",
        "label": "SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Text Block]",
        "terseLabel": "Mortgage Banking Activities"
       }
      }
     },
     "localname": "MortgageLoansOnRealEstateByLoanDisclosureTextBlock",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/MortgageBankingActivities"
     ],
     "xbrltype": "textBlockItemType"
    },
    "srt_ProductOrServiceAxis": {
     "auth_ref": [
      "r162",
      "r298",
      "r299",
      "r491",
      "r564",
      "r566"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by product and service, or group of similar products and similar services.",
        "label": "Product and Service [Axis]",
        "terseLabel": "Product and Service [Axis]"
       }
      }
     },
     "localname": "ProductOrServiceAxis",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails",
      "http://www.firstib.com/role/ServicingAssetNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_ProductsAndServicesDomain": {
     "auth_ref": [
      "r162",
      "r298",
      "r299",
      "r491",
      "r564",
      "r566"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Product or service, or a group of similar products or similar services.",
        "label": "Product and Service [Domain]",
        "terseLabel": "Product and Service [Domain]"
       }
      }
     },
     "localname": "ProductsAndServicesDomain",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails",
      "http://www.firstib.com/role/ServicingAssetNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_RangeAxis": {
     "auth_ref": [
      "r306",
      "r316",
      "r317",
      "r446",
      "r447",
      "r448",
      "r452",
      "r453",
      "r454",
      "r490",
      "r565",
      "r567"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by statistical measurement. Includes, but is not limited to, minimum, maximum, weighted average, arithmetic average, and median.",
        "label": "Statistical Measurement [Axis]",
        "terseLabel": "Statistical Measurement [Axis]"
       }
      }
     },
     "localname": "RangeAxis",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
      "http://www.firstib.com/role/LeasesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_RangeMember": {
     "auth_ref": [
      "r306",
      "r316",
      "r317",
      "r446",
      "r447",
      "r448",
      "r452",
      "r453",
      "r454",
      "r490",
      "r565",
      "r567"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Statistical measurement. Includes, but is not limited to, minimum, maximum, weighted average, arithmetic average, and median.",
        "label": "Statistical Measurement [Domain]",
        "terseLabel": "Statistical Measurement [Domain]"
       }
      }
     },
     "localname": "RangeMember",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
      "http://www.firstib.com/role/LeasesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_RepurchaseAgreementCounterpartyNameDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Named other party that participates in a financial transaction. Examples include, but not limited to, the name of the financial institution.",
        "label": "Counterparty Name [Domain]",
        "terseLabel": "Counterparty Name [Domain]"
       }
      }
     },
     "localname": "RepurchaseAgreementCounterpartyNameDomain",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_SubsidiariesMember": {
     "auth_ref": [
      "r314",
      "r435",
      "r436",
      "r438"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Entity owned or controlled by another entity.",
        "label": "Subsidiaries [Member]",
        "terseLabel": "SPF15, Inc."
       }
      }
     },
     "localname": "SubsidiariesMember",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_TitleOfIndividualAxis": {
     "auth_ref": [
      "r165",
      "r437"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by title of individual or nature of relationship to individual or group of individuals.",
        "label": "Title of Individual [Axis]",
        "terseLabel": "Title of Individual [Axis]"
       }
      }
     },
     "localname": "TitleOfIndividualAxis",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_TitleOfIndividualWithRelationshipToEntityDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Title of individual, or nature of relationship to individual or group of individuals.",
        "label": "Title of Individual [Domain]",
        "terseLabel": "Title of Individual [Domain]"
       }
      }
     },
     "localname": "TitleOfIndividualWithRelationshipToEntityDomain",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_WeightedAverageMember": {
     "auth_ref": [
      "r446",
      "r448",
      "r454"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Average of a range of values, calculated with consideration of proportional relevance.",
        "label": "Weighted Average [Member]",
        "terseLabel": "Weighted-Average Range"
       }
      }
     },
     "localname": "WeightedAverageMember",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AOCIAttributableToParentNetOfTaxRollForward": {
     "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": "AOCI Attributable to Parent, Net of Tax [Roll Forward]",
        "terseLabel": "AOCI Attributable to Parent, Net of Tax [Roll Forward]"
       }
      }
     },
     "localname": "AOCIAttributableToParentNetOfTaxRollForward",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccountingStandardsUpdate201708Member": {
     "auth_ref": [
      "r193"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Accounting Standards Update 2017-08 Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.",
        "label": "Accounting Standards Update 2017-08 [Member]",
        "terseLabel": "Accounting Standards Update 2017-08"
       }
      }
     },
     "localname": "AccountingStandardsUpdate201708Member",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "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, Loans and Financing Receivable [Line Items]",
        "terseLabel": "Accounts, Notes, Loans and Financing Receivable [Line Items]"
       }
      }
     },
     "localname": "AccountsNotesAndLoansReceivableLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccruedLiabilitiesAndOtherLiabilities": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 5.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of expenses incurred but not yet paid nor invoiced, and liabilities classified as other.",
        "label": "Accrued Liabilities and Other Liabilities",
        "verboseLabel": "Accrued expenses and other liabilities"
       }
      }
     },
     "localname": "AccruedLiabilitiesAndOtherLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment": {
     "auth_ref": [
      "r19",
      "r264"
     ],
     "calculation": {
      "http://www.firstib.com/role/SummaryDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_PropertyPlantAndEquipmentNet",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.",
        "label": "Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment",
        "negatedLabel": "Less: accumulated depreciation"
       }
      }
     },
     "localname": "AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember": {
     "auth_ref": [
      "r45",
      "r55",
      "r359"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Accumulated other comprehensive income (loss) from gain (loss) of derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness, attributable to parent.",
        "label": "Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]",
        "terseLabel": "Cash Flow Hedges"
       }
      }
     },
     "localname": "AccumulatedGainLossNetCashFlowHedgeParentMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember": {
     "auth_ref": [
      "r38",
      "r39",
      "r40",
      "r45",
      "r48"
     ],
     "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": "AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]",
        "terseLabel": "Available-For-Sale Securities"
       }
      }
     },
     "localname": "AccumulatedNetUnrealizedInvestmentGainLossMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax": {
     "auth_ref": [
      "r13",
      "r42",
      "r44",
      "r45",
      "r551",
      "r575",
      "r579"
     ],
     "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",
        "verboseLabel": "Accumulated other comprehensive loss"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeLossNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeLossTable": {
     "auth_ref": [
      "r410",
      "r411",
      "r412",
      "r413",
      "r414",
      "r416"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeMember": {
     "auth_ref": [
      "r41",
      "r45",
      "r48",
      "r100",
      "r101",
      "r102",
      "r360",
      "r570",
      "r571"
     ],
     "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": "AOCI Attributable to Parent [Member]",
        "terseLabel": "Accumulated Other Comprehensive Loss"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AdjustmentsForNewAccountingPronouncementsAxis": {
     "auth_ref": [
      "r106",
      "r107",
      "r108",
      "r110",
      "r229",
      "r230",
      "r231",
      "r232",
      "r235",
      "r236",
      "r333",
      "r334",
      "r335",
      "r336",
      "r337",
      "r338",
      "r339",
      "r341",
      "r344",
      "r345",
      "r346",
      "r347",
      "r492",
      "r493",
      "r494",
      "r568",
      "r569",
      "r570",
      "r571",
      "r572",
      "r573",
      "r574",
      "r575",
      "r576",
      "r577",
      "r578",
      "r579"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by amendment to accounting standards.",
        "label": "Accounting Standards Update [Axis]",
        "terseLabel": "Adjustments for New Accounting Pronouncements [Axis]"
       }
      }
     },
     "localname": "AdjustmentsForNewAccountingPronouncementsAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]",
        "verboseLabel": "Adjustments to reconcile net income to net cash used in operating activities:"
       }
      }
     },
     "localname": "AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of decrease to equity for grantee's tax withholding obligation for award under share-based payment arrangement.",
        "label": "Share-based Payment Arrangement, Decrease for Tax Withholding Obligation",
        "negatedLabel": "Common stock redeemed for the net settlement of share-based awards"
       }
      }
     },
     "localname": "AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AdvancesFromFederalHomeLoanBanks": {
     "auth_ref": [
      "r545"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "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": "Advances from Federal Home Loan Bank"
       }
      }
     },
     "localname": "AdvancesFromFederalHomeLoanBanks",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock": {
     "auth_ref": [
      "r173",
      "r239"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of allowance for credit loss on financing receivable.",
        "label": "Financing Receivable, Allowance for Credit Loss [Table Text Block]",
        "terseLabel": "Allowance for Credit Losses on Financing Receivables"
       }
      }
     },
     "localname": "AllowanceForCreditLossesOnFinancingReceivablesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts": {
     "auth_ref": [
      "r170"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.",
        "label": "Allowance for Loan and Lease Loss, Recovery of Bad Debts",
        "verboseLabel": "Recoveries"
       }
      }
     },
     "localname": "AllowanceForLoanAndLeaseLossRecoveryOfBadDebts",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AllowanceForLoanAndLeaseLossesRollForward": {
     "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": "Allowance for Loan and Lease Losses [Roll Forward]",
        "terseLabel": "Allowance for loan losses:"
       }
      }
     },
     "localname": "AllowanceForLoanAndLeaseLossesRollForward",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs": {
     "auth_ref": [
      "r169"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.",
        "label": "Allowance for Loan and Lease Losses, Write-offs",
        "negatedLabel": "Losses charged off"
       }
      }
     },
     "localname": "AllowanceForLoanAndLeaseLossesWriteOffs",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount": {
     "auth_ref": [
      "r135"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.",
        "label": "Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount",
        "terseLabel": "Antidilutive securities excluded from computation of earnings per share, amount (in shares)"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/EarningsPerShareDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis": {
     "auth_ref": [
      "r135"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of antidilutive security.",
        "label": "Antidilutive Securities [Axis]",
        "terseLabel": "Antidilutive Securities [Axis]"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AntidilutiveSecuritiesNameDomain": {
     "auth_ref": [
      "r135"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Incremental common shares attributable to securities that were not included in diluted earnings per share (EPS) because to do so would increase EPS amounts or decrease loss per share amounts for the period presented.",
        "label": "Antidilutive Securities, Name [Domain]",
        "terseLabel": "Antidilutive Securities, Name [Domain]"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AreaOfLand": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Area of land held.",
        "label": "Area of Land",
        "terseLabel": "Area of land"
       }
      }
     },
     "localname": "AreaOfLand",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "areaItemType"
    },
    "us-gaap_AssetBackedSecuritiesMember": {
     "auth_ref": [
      "r212",
      "r307"
     ],
     "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": "Asset-backed securities"
       }
      }
     },
     "localname": "AssetBackedSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails",
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_Assets": {
     "auth_ref": [
      "r93",
      "r151",
      "r154",
      "r160",
      "r228",
      "r357",
      "r361",
      "r408",
      "r504",
      "r549"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AssetsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Assets [Abstract]",
        "verboseLabel": "Assets"
       }
      }
     },
     "localname": "AssetsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AssetsSoldUnderAgreementsToRepurchaseAxis": {
     "auth_ref": [
      "r98"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by securities or other assets sold under repurchase agreements. Repurchase agreements are agreements under which the transferor (repo party) transfers a security to a transferee (repo counterparty or reverse party) in exchange for cash and concurrently agrees to reacquire that security at a future date for an amount equal to the cash exchanged plus a stipulated interest factor.",
        "label": "Securities or Other Assets Sold under Agreements to Repurchase [Axis]",
        "terseLabel": "Securities or Other Assets Sold under Agreements to Repurchase [Axis]"
       }
      }
     },
     "localname": "AssetsSoldUnderAgreementsToRepurchaseAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AssetsSoldUnderAgreementsToRepurchaseTypeDomain": {
     "auth_ref": [
      "r98"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This is the type of such assets (for example, US Treasury Obligations, US Government agency obligations and loans, and so forth). This item may be presented as an element in the table that is disclosed when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under repurchase agreements exceed 10 percent of total assets, as of the most recent balance sheet date.",
        "label": "Assets Sold under Agreements to Repurchase, Type [Domain]",
        "terseLabel": "Assets Sold under Agreements to Repurchase, Type [Domain]"
       }
      }
     },
     "localname": "AssetsSoldUnderAgreementsToRepurchaseTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax": {
     "auth_ref": [
      "r202"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesDetails": {
       "order": 1.0,
       "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": "Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax",
        "terseLabel": "Gross Unrealized Gains"
       }
      }
     },
     "localname": "AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax": {
     "auth_ref": [
      "r203"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesDetails": {
       "order": 2.0,
       "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": "Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax",
        "negatedLabel": "Gross Unrealized Losses"
       }
      }
     },
     "localname": "AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis": {
     "auth_ref": [
      "r200",
      "r252"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesDetails": {
       "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": "Debt Securities, Available-for-sale, Amortized Cost",
        "terseLabel": "Amortized cost",
        "totalLabel": "Amortized cost"
       }
      }
     },
     "localname": "AvailableForSaleDebtSecuritiesAmortizedCostBasis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecurities": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.",
        "label": "Available-for-sale Securities",
        "verboseLabel": "Securities available-for-sale, at fair value (amortized cost of $590,046 and $546,640 in 2020 and 2019, respectively)"
       }
      }
     },
     "localname": "AvailableForSaleSecurities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesAmortizedCost": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.",
        "label": "Available-for-sale Securities, Amortized Cost Basis",
        "terseLabel": "Amortized cost, at fair value"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesAmortizedCost",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Debt Securities, Available-for-sale, Maturity, Amortized Cost, Rolling Maturity [Abstract]",
        "terseLabel": "Amortized Cost"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Debt Securities, Available-for-sale, Maturity, Fair Value, Rolling Maturity [Abstract]",
        "terseLabel": "Fair Value"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 4.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis",
       "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 next rolling fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Amortized Cost",
        "terseLabel": "Within one year"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 4.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate",
       "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 next rolling fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value",
        "terseLabel": "Within one year"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis",
       "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 rolling tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost",
        "terseLabel": "After ten years"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate",
       "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 rolling tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value",
        "terseLabel": "After ten years"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis",
       "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 rolling sixth through tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Amortized Cost",
        "terseLabel": "Five to ten years"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate",
       "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 rolling sixth through tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value",
        "terseLabel": "Five to ten years"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis",
       "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 next rolling fiscal year through fifth year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost",
        "terseLabel": "One to five years"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate",
       "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 next rolling fiscal year through fifth year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value",
        "terseLabel": "One to five years"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate": {
     "auth_ref": [
      "r204",
      "r205",
      "r542"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "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.",
        "label": "Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value",
        "totalLabel": "Fair Value"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis": {
     "auth_ref": [
      "r204",
      "r205",
      "r540"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "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), with single maturity date and allocated without single maturity date.",
        "label": "Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost",
        "totalLabel": "Amortized Cost"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtSecurities": {
     "auth_ref": [
      "r196",
      "r201",
      "r252",
      "r508"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "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": "Debt Securities, Available-for-sale",
        "terseLabel": "Fair Value",
        "verboseLabel": "Total available-for-sale securities"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtSecurities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesFairValueToAmortizedCostBasisAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]",
        "terseLabel": "Available-for-sale Securities [Abstract]"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesFairValueToAmortizedCostBasisAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AvailableforsaleSecuritiesMember": {
     "auth_ref": [
      "r223"
     ],
     "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": "Available-for-sale Securities [Member]",
        "terseLabel": "Securities available-for-sale"
       }
      }
     },
     "localname": "AvailableforsaleSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AwardTypeAxis": {
     "auth_ref": [
      "r321",
      "r332"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of award under share-based payment arrangement.",
        "label": "Award Type [Axis]",
        "terseLabel": "Award Type [Axis]"
       }
      }
     },
     "localname": "AwardTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails",
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "stringItemType"
    },
    "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 [Axis]"
       }
      }
     },
     "localname": "BalanceSheetLocationAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "BalanceSheetLocationDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_BankOwnedLifeInsurance": {
     "auth_ref": [
      "r503"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 7.0,
       "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",
        "verboseLabel": "Cash surrender value of bank-owned life insurance"
       }
      }
     },
     "localname": "BankOwnedLifeInsurance",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_BankServicingMember": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Collection and processing of payment on mortgage, credit card and other financial asset held by others.",
        "label": "Bank Servicing [Member]",
        "terseLabel": "Service charges and fees"
       }
      }
     },
     "localname": "BankServicingMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_BuildingImprovementsMember": {
     "auth_ref": [
      "r263"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Addition, improvement, or renovation to a facility held for productive use including, but not limited to, office, production, storage and distribution facilities.",
        "label": "Building Improvements [Member]",
        "terseLabel": "Building and improvements"
       }
      }
     },
     "localname": "BuildingImprovementsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CapitalAdditionsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Contractual obligation to increase property, plant and equipment either through construction or future purchases.",
        "label": "Capital Addition Purchase Commitments [Member]",
        "terseLabel": "Capital Addition Purchase Commitments"
       }
      }
     },
     "localname": "CapitalAdditionsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRiskDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CarryingReportedAmountFairValueDisclosureMember": {
     "auth_ref": [
      "r406",
      "r407"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measured as reported on the statement of financial position (balance sheet).",
        "label": "Reported Value Measurement [Member]",
        "terseLabel": "Reported Value Measurement"
       }
      }
     },
     "localname": "CarryingReportedAmountFairValueDisclosureMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CashAndCashEquivalentsAtCarryingValue": {
     "auth_ref": [
      "r2",
      "r17",
      "r85"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 1.0,
       "parentTag": "us-gaap_Assets",
       "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. 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. Excludes cash and cash equivalents within disposal group and discontinued operation.",
        "label": "Cash and Cash Equivalents, at Carrying Value",
        "terseLabel": "Cash and cash equivalents, Carrying Amount",
        "totalLabel": "Total cash and cash equivalents"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAtCarryingValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashAndCashEquivalentsFairValueDisclosure": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. 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": "Cash and Cash Equivalents, Fair Value Disclosure",
        "terseLabel": "Cash and cash equivalents, Fair Value"
       }
      }
     },
     "localname": "CashAndCashEquivalentsFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashAndDueFromBanks": {
     "auth_ref": [
      "r501"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 1.0,
       "parentTag": "us-gaap_CashAndCashEquivalentsAtCarryingValue",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "For banks and other depository institutions: Includes cash on hand (currency and coin), 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",
        "verboseLabel": "Cash and due from banks"
       }
      }
     },
     "localname": "CashAndDueFromBanks",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents": {
     "auth_ref": [
      "r78",
      "r85",
      "r91"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for 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",
        "periodEndLabel": "Cash and Cash Equivalents, End of Period",
        "periodStartLabel": "Cash and Cash Equivalents, Beginning of Period"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect": {
     "auth_ref": [
      "r78",
      "r409"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "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": "Net Increase in Cash and Cash Equivalents"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ClassOfStockDomain": {
     "auth_ref": [
      "r92",
      "r93",
      "r125",
      "r129",
      "r130",
      "r132",
      "r134",
      "r143",
      "r144",
      "r145",
      "r228",
      "r408"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "ClassOfStockDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited",
      "http://www.firstib.com/role/Cover"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ClassOfStockLineItems": {
     "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": "Class of Stock [Line Items]",
        "terseLabel": "Class of Stock [Line Items]"
       }
      }
     },
     "localname": "ClassOfStockLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/Cover"
     ],
     "xbrltype": "stringItemType"
    },
    "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 Portfolio Segment"
       }
      }
     },
     "localname": "CommercialPortfolioSegmentMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommercialRealEstateMember": {
     "auth_ref": [
      "r248",
      "r307"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Property that is solely used for business purposes.",
        "label": "Commercial Real Estate [Member]",
        "terseLabel": "Commercial and industrial"
       }
      }
     },
     "localname": "CommercialRealEstateMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommitmentsAndContingencies": {
     "auth_ref": [
      "r23",
      "r271",
      "r513",
      "r555"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 3.0,
       "parentTag": "us-gaap_LiabilitiesAndStockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Represents the caption on the face of the balance sheet to indicate that the entity has entered into (1) purchase or supply arrangements that will require expending a portion of its resources to meet the terms thereof, and (2) is exposed to potential losses or, less frequently, gains, arising from (a) possible claims against a company's resources due to future performance under contract terms, and (b) possible losses or likely gains from uncertainties that will ultimately be resolved when one or more future events that are deemed likely to occur do occur or fail to occur.",
        "label": "Commitments and Contingencies",
        "terseLabel": "Commitments and Contingencies"
       }
      }
     },
     "localname": "CommitmentsAndContingencies",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CommitmentsAndContingenciesDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Commitments and Contingencies Disclosure [Abstract]",
        "terseLabel": "Commitments and Contingencies Disclosure [Abstract]"
       }
      }
     },
     "localname": "CommitmentsAndContingenciesDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_CommitmentsAndContingenciesDisclosureTextBlock": {
     "auth_ref": [
      "r268",
      "r269",
      "r270",
      "r278"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for commitments and contingencies.",
        "label": "Commitments and Contingencies Disclosure [Text Block]",
        "terseLabel": "Commitments and Credit Risk"
       }
      }
     },
     "localname": "CommitmentsAndContingenciesDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRisk"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CommonStockDividendsPerShareDeclared": {
     "auth_ref": [
      "r296"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate dividends declared during the period for each share of common stock outstanding.",
        "label": "Common Stock, Dividends, Per Share, Declared",
        "terseLabel": "Dividends Declared Per Share (in dollars per share)",
        "verboseLabel": "Dividends declared (in dollars per share)"
       }
      }
     },
     "localname": "CommonStockDividendsPerShareDeclared",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/ConsolidatedStatementsofShareholdersEquityUnauditedParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_CommonStockMember": {
     "auth_ref": [
      "r100",
      "r101"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Stock that is subordinate to all other stock of the issuer.",
        "label": "Common Stock [Member]",
        "terseLabel": "Voting\u00a0and Nonvoting Common Stock",
        "verboseLabel": "Common Stock"
       }
      }
     },
     "localname": "CommonStockMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited",
      "http://www.firstib.com/role/Cover"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommonStockParOrStatedValuePerShare": {
     "auth_ref": [
      "r11"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_CommonStockSharesAuthorized": {
     "auth_ref": [
      "r11"
     ],
     "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",
        "verboseLabel": "Common stock, shares authorized (in shares)"
       }
      }
     },
     "localname": "CommonStockSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockSharesIssued": {
     "auth_ref": [
      "r11"
     ],
     "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",
        "verboseLabel": "Common stock, shares issued (in shares)"
       }
      }
     },
     "localname": "CommonStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockSharesOutstanding": {
     "auth_ref": [
      "r11",
      "r289"
     ],
     "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",
        "verboseLabel": "Common stock, shares outstanding (in shares)"
       }
      }
     },
     "localname": "CommonStockSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockValue": {
     "auth_ref": [
      "r11"
     ],
     "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, Issued",
        "terseLabel": "Common stock"
       }
      }
     },
     "localname": "CommonStockValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CompensationAndEmployeeBenefitPlansTextBlock": {
     "auth_ref": [
      "r304",
      "r305",
      "r318",
      "r342"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for an entity's employee compensation and benefit plans, including, but not limited to, postemployment and postretirement benefit plans, defined benefit pension plans, defined contribution plans, non-qualified and supplemental benefit plans, deferred compensation, share-based compensation, life insurance, severance, health care, unemployment and other benefit plans.",
        "label": "Compensation and Employee Benefit Plans [Text Block]",
        "terseLabel": "Benefit Plans"
       }
      }
     },
     "localname": "CompensationAndEmployeeBenefitPlansTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlans"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CompensationAndRetirementDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Retirement Benefits [Abstract]",
        "terseLabel": "Retirement Benefits [Abstract]"
       }
      }
     },
     "localname": "CompensationAndRetirementDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_ComprehensiveIncomeNetOfTax": {
     "auth_ref": [
      "r51",
      "r53",
      "r54",
      "r60",
      "r520",
      "r559"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited": {
       "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 (Loss), Net of Tax, Attributable to Parent",
        "totalLabel": "Comprehensive income"
       }
      }
     },
     "localname": "ComprehensiveIncomeNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ComprehensiveIncomeNoteTextBlock": {
     "auth_ref": [
      "r59",
      "r65",
      "r519",
      "r558"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.",
        "label": "Comprehensive Income (Loss) Note [Text Block]",
        "terseLabel": "Accumulated Other Comprehensive Loss"
       }
      }
     },
     "localname": "ComprehensiveIncomeNoteTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLoss"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ConstructionLoansMember": {
     "auth_ref": [
      "r585"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A borrowing arrangement which provides the entity constructing a facility (such as a building and a landfill) with funds to effect construction, generally on a draw down, or as needed, basis.",
        "label": "Construction Loans [Member]",
        "terseLabel": "Construction"
       }
      }
     },
     "localname": "ConstructionLoansMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "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 Portfolio"
       }
      }
     },
     "localname": "ConsumerPortfolioSegmentMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ContractualObligation": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.",
        "label": "Contractual Obligation",
        "terseLabel": "Loan commitments"
       }
      }
     },
     "localname": "ContractualObligation",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRiskDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CorporateDebtSecuritiesMember": {
     "auth_ref": [
      "r307",
      "r315",
      "r580"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt securities issued by domestic or foreign corporate business, banks and other entities with a promise of repayment.",
        "label": "Corporate Debt Securities [Member]",
        "terseLabel": "Corporate securities"
       }
      }
     },
     "localname": "CorporateDebtSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/SecuritiesDetails",
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DebtDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Debt Disclosure [Abstract]",
        "terseLabel": "Debt Disclosure [Abstract]"
       }
      }
     },
     "localname": "DebtDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtInstrumentAxis": {
     "auth_ref": [
      "r6",
      "r7",
      "r8",
      "r505",
      "r506",
      "r547"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of debt instrument, including, but not limited to, draws against credit facilities.",
        "label": "Debt Instrument [Axis]",
        "terseLabel": "Debt Instrument [Axis]"
       }
      }
     },
     "localname": "DebtInstrumentAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "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 Rate",
        "terseLabel": "Basis spread on variable rate"
       }
      }
     },
     "localname": "DebtInstrumentBasisSpreadOnVariableRate1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_DebtInstrumentFaceAmount": {
     "auth_ref": [
      "r419",
      "r421"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Face (par) amount of debt instrument at time of issuance.",
        "label": "Debt Instrument, Face Amount",
        "terseLabel": "Subordinated debenture, principal amount"
       }
      }
     },
     "localname": "DebtInstrumentFaceAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtInstrumentInterestRateStatedPercentage": {
     "auth_ref": [
      "r21"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Contractual interest rate for funds borrowed, under the debt agreement.",
        "label": "Debt Instrument, Interest Rate, Stated Percentage",
        "terseLabel": "Fixed annual interest rate (as a percent)"
       }
      }
     },
     "localname": "DebtInstrumentInterestRateStatedPercentage",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual"
     ],
     "xbrltype": "percentItemType"
    },
    "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtInstrumentNameDomain": {
     "auth_ref": [
      "r22"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The name for the particular debt instrument or borrowing that distinguishes it from other debt instruments or borrowings, including draws against credit facilities.",
        "label": "Debt Instrument, Name [Domain]",
        "terseLabel": "Debt Instrument, Name [Domain]"
       }
      }
     },
     "localname": "DebtInstrumentNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DebtInstrumentTable": {
     "auth_ref": [
      "r22",
      "r96",
      "r290",
      "r293",
      "r294",
      "r295",
      "r418",
      "r419",
      "r421",
      "r546"
     ],
     "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": "Schedule of Long-term Debt Instruments [Table]",
        "terseLabel": "Schedule of Long-term Debt Instruments [Table]"
       }
      }
     },
     "localname": "DebtInstrumentTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtInstrumentUnamortizedDiscount": {
     "auth_ref": [
      "r418",
      "r421"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after accumulated amortization, of debt discount.",
        "label": "Debt Instrument, Unamortized Discount",
        "negatedTerseLabel": "Unamortized Debt Issuance Costs",
        "terseLabel": "Unamortized discounts and debt issuance costs"
       }
      }
     },
     "localname": "DebtInstrumentUnamortizedDiscount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger": {
     "auth_ref": [
      "r222",
      "r256",
      "r259"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition",
       "weight": 1.0
      }
     },
     "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 Position, 12 Months or Longer",
        "verboseLabel": "12 Months or Longer, Fair Value"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss": {
     "auth_ref": [
      "r222",
      "r256"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss",
       "weight": 1.0
      }
     },
     "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 Position, 12 Months or Longer, Accumulated Loss",
        "negatedLabel": "12 Months or Longer, Unrealized Losses"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months": {
     "auth_ref": [
      "r222",
      "r256",
      "r259"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition",
       "weight": 1.0
      }
     },
     "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 than 12 Months",
        "verboseLabel": "Less Than 12 Months, Fair Value"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss": {
     "auth_ref": [
      "r222",
      "r256"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss",
       "weight": 1.0
      }
     },
     "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 than 12 Months, Accumulated Loss",
        "negatedLabel": "Less Than 12 Months, Unrealized Losses"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss": {
     "auth_ref": [
      "r224"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 4.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      },
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 4.0,
       "parentTag": "us-gaap_NoninterestIncome",
       "weight": 1.0
      }
     },
     "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).",
        "label": "Debt Securities, Available-for-sale, Realized Gain (Loss)",
        "negatedLabel": "(Loss) gain on sale of available-for-sale securities",
        "netLabel": "Gain (loss) realized in earnings",
        "terseLabel": "(Loss) gain on sale of securities",
        "verboseLabel": "Available-for-sale securities, gross realized gain (loss)"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleRealizedGainLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/SecuritiesDetailsTextual",
      "http://www.firstib.com/role/SecuritiesSecuritiesAmountsReclassifiedfromAccumulatedOtherComprehensiveIncomeLossDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleTableTextBlock": {
     "auth_ref": [
      "r226"
     ],
     "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": "Available-for-sale Securities"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition": {
     "auth_ref": [
      "r220",
      "r253",
      "r259"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "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), in unrealized loss position without allowance for credit loss.",
        "label": "Debt Securities, Available-for-sale, Unrealized Loss Position",
        "totalLabel": "Total, Fair Value"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleUnrealizedLossPosition",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss": {
     "auth_ref": [
      "r221",
      "r254"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "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 unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.",
        "label": "Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss",
        "negatedTotalLabel": "Total, Unrealized Losses"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTableTextBlock": {
     "auth_ref": [
      "r219",
      "r255",
      "r259"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.",
        "label": "Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block]",
        "terseLabel": "Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_Deposits": {
     "auth_ref": [
      "r510"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 1.0,
       "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, Carrying Amount",
        "totalLabel": "Total deposits"
       }
      }
     },
     "localname": "Deposits",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DepositsFairValueDisclosure": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.",
        "label": "Deposits, Fair Value Disclosure",
        "terseLabel": "Deposits, Fair Value"
       }
      }
     },
     "localname": "DepositsFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DepositsMember": {
     "auth_ref": [
      "r537"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amounts held on account by the entity representing a liability to the depositor. Deposits may take various forms (for example, demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits) and may be categorized in multiple ways (such as, foreign and domestic, interest and noninterest bearing).",
        "label": "Deposits [Member]",
        "terseLabel": "Deposits"
       }
      }
     },
     "localname": "DepositsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DepreciationDepletionAndAmortization": {
     "auth_ref": [
      "r83",
      "r149"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 14.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.",
        "label": "Depreciation, Depletion and Amortization",
        "verboseLabel": "Depreciation and amortization"
       }
      }
     },
     "localname": "DepreciationDepletionAndAmortization",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeAssetNotionalAmount": {
     "auth_ref": [
      "r364",
      "r365",
      "r366"
     ],
     "calculation": {
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_DerivativeNotionalAmount",
       "weight": 1.0
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Nominal or face amount used to calculate payments on the derivative asset.",
        "label": "Derivative Asset, Notional Amount",
        "verboseLabel": "Notional Amount"
       }
      }
     },
     "localname": "DerivativeAssetNotionalAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeAssets": {
     "auth_ref": [
      "r29",
      "r31",
      "r405"
     ],
     "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 Asset",
        "terseLabel": "Carrying amount of the hedged assets"
       }
      }
     },
     "localname": "DerivativeAssets",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeAssetsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Derivative Asset [Abstract]",
        "verboseLabel": "Asset Derivatives"
       }
      }
     },
     "localname": "DerivativeAssetsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeAverageFixedInterestRate": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Average fixed interest rate related to the group of interest rate derivatives.",
        "label": "Derivative, Average Fixed Interest Rate",
        "terseLabel": "Weighted-Average Rate"
       }
      }
     },
     "localname": "DerivativeAverageFixedInterestRate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_DerivativeAverageRemainingMaturity1": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.",
        "label": "Derivative, Average Remaining Maturity",
        "terseLabel": "Weighted Average Remaining Maturity (years)"
       }
      }
     },
     "localname": "DerivativeAverageRemainingMaturity1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_DerivativeCollateralObligationToReturnCash": {
     "auth_ref": [
      "r30",
      "r32",
      "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",
        "terseLabel": "Cash collateral pledged"
       }
      }
     },
     "localname": "DerivativeCollateralObligationToReturnCash",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeCollateralRightToReclaimCash": {
     "auth_ref": [
      "r30",
      "r32",
      "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 received"
       }
      }
     },
     "localname": "DerivativeCollateralRightToReclaimCash",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails"
     ],
     "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 [Domain]",
        "terseLabel": "Derivative Contract [Domain]"
       }
      }
     },
     "localname": "DerivativeContractTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/LoansCategoriesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral": {
     "auth_ref": [
      "r29",
      "r31",
      "r35",
      "r388"
     ],
     "calculation": {
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_DerivativeFairValueOfDerivativeNet",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value, after offset of derivative liability, 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, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.",
        "label": "Derivative Asset, Fair Value, Amount Not Offset Against Collateral",
        "verboseLabel": "Fair Value"
       }
      }
     },
     "localname": "DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeFairValueOfDerivativeLiability": {
     "auth_ref": [
      "r28",
      "r34",
      "r371",
      "r457"
     ],
     "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 Liability, Fair Value, Gross Liability",
        "negatedTerseLabel": "Derivative liability, fair value"
       }
      }
     },
     "localname": "DerivativeFairValueOfDerivativeLiability",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral": {
     "auth_ref": [
      "r29",
      "r31",
      "r35",
      "r388"
     ],
     "calculation": {
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_DerivativeFairValueOfDerivativeNet",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value, after offset of derivative asset, 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, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.",
        "label": "Derivative Liability, Fair Value, Amount Not Offset Against Collateral",
        "terseLabel": "Fair Value"
       }
      }
     },
     "localname": "DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeFairValueOfDerivativeNet": {
     "auth_ref": [
      "r405"
     ],
     "calculation": {
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of the assets less the liabilities of a derivative or group of derivatives.",
        "label": "Derivative, Fair Value, Net",
        "terseLabel": "Derivative, fair value",
        "totalLabel": "Derivative, fair value",
        "verboseLabel": "Fair Value"
       }
      }
     },
     "localname": "DerivativeFairValueOfDerivativeNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "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": "Asset Derivatives"
       }
      }
     },
     "localname": "DerivativeFinancialInstrumentsAssetsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails"
     ],
     "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": "Liability Derivatives"
       }
      }
     },
     "localname": "DerivativeFinancialInstrumentsLiabilitiesMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DerivativeGainLossOnDerivativeNet": {
     "auth_ref": [
      "r370"
     ],
     "calculation": {
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax",
       "weight": 1.0
      }
     },
     "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": "Gain (loss) resulting from the change in fair value of derivatives"
       }
      }
     },
     "localname": "DerivativeGainLossOnDerivativeNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails",
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeInstrumentRiskAxis": {
     "auth_ref": [
      "r369",
      "r372",
      "r379",
      "r384"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of derivative contract.",
        "label": "Derivative Instrument [Axis]",
        "terseLabel": "Derivative Instrument [Axis]"
       }
      }
     },
     "localname": "DerivativeInstrumentRiskAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/LoansCategoriesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Derivative Instruments and Hedging Activities Disclosure [Abstract]",
        "terseLabel": "Derivative Instruments and Hedging Activities Disclosure [Abstract]"
       }
      }
     },
     "localname": "DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock": {
     "auth_ref": [
      "r394"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstruments"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems": {
     "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 and Hedging Activities Disclosures [Line Items]",
        "terseLabel": "Derivative Instruments and Hedging Activities Disclosures [Line Items]"
       }
      }
     },
     "localname": "DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about derivatives and hedging activities.",
        "label": "Derivative Instruments and Hedging Activities Disclosures [Table]",
        "terseLabel": "Derivative Instruments and Hedging Activities Disclosures [Table]"
       }
      }
     },
     "localname": "DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable": {
     "auth_ref": [
      "r367",
      "r369",
      "r379",
      "r384",
      "r385",
      "r389",
      "r392"
     ],
     "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) [Table]",
        "terseLabel": "Derivative Instruments, Gain (Loss) [Table]"
       }
      }
     },
     "localname": "DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "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]"
       }
      }
     },
     "localname": "DerivativeInstrumentsGainLossLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet": {
     "auth_ref": [
      "r377",
      "r391"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.",
        "label": "Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net",
        "terseLabel": "Gain (loss) recognized on the condensed consolidated statements of income"
       }
      }
     },
     "localname": "DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet": {
     "auth_ref": [
      "r378",
      "r380"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.",
        "label": "Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net",
        "terseLabel": "Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net"
       }
      }
     },
     "localname": "DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeLiabilitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Derivative Liability [Abstract]",
        "terseLabel": "Derivative Liability [Abstract]"
       }
      }
     },
     "localname": "DerivativeLiabilitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DerivativeLiabilityNotionalAmount": {
     "auth_ref": [
      "r364",
      "r365",
      "r366"
     ],
     "calculation": {
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_DerivativeNotionalAmount",
       "weight": 1.0
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Nominal or face amount used to calculate payments on the derivative liability.",
        "label": "Derivative Liability, Notional Amount",
        "terseLabel": "Notional Amount"
       }
      }
     },
     "localname": "DerivativeLiabilityNotionalAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeNotionalAmount": {
     "auth_ref": [
      "r365",
      "r366"
     ],
     "calculation": {
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Nominal or face amount used to calculate payment on derivative.",
        "label": "Derivative, Notional Amount",
        "terseLabel": "Notional Value",
        "totalLabel": "Notional Amount"
       }
      }
     },
     "localname": "DerivativeNotionalAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DerivativeVariableInterestRate": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Variable interest rate in effect as of the balance sheet date related to the interest rate derivative.",
        "label": "Derivative, Variable Interest Rate",
        "terseLabel": "Derivative, variable interest rate"
       }
      }
     },
     "localname": "DerivativeVariableInterestRate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "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"
       }
      }
     },
     "localname": "DesignatedAsHedgingInstrumentMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DividendsCommonStockCash": {
     "auth_ref": [
      "r296"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.",
        "label": "Dividends, Common Stock, Cash",
        "negatedLabel": "Dividends declared"
       }
      }
     },
     "localname": "DividendsCommonStockCash",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EarningsPerShareAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Earnings Per Share [Abstract]",
        "terseLabel": "Earnings Per Share [Abstract]"
       }
      }
     },
     "localname": "EarningsPerShareAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_EarningsPerShareBasic": {
     "auth_ref": [
      "r61",
      "r112",
      "r113",
      "r114",
      "r115",
      "r116",
      "r123",
      "r125",
      "r132",
      "r133",
      "r134",
      "r139",
      "r140",
      "r521",
      "r560"
     ],
     "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",
        "terseLabel": "Basic (in dollars per share)",
        "verboseLabel": "Basic earnings per common share ( in dollars per share)"
       }
      }
     },
     "localname": "EarningsPerShareBasic",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/EarningsPerShareDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_EarningsPerShareBasicAndDilutedAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Earnings Per Share, Basic and Diluted [Abstract]",
        "verboseLabel": "Income Per Share of Common Stock"
       }
      }
     },
     "localname": "EarningsPerShareBasicAndDilutedAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EarningsPerShareDiluted": {
     "auth_ref": [
      "r61",
      "r112",
      "r113",
      "r114",
      "r115",
      "r116",
      "r125",
      "r132",
      "r133",
      "r134",
      "r139",
      "r140",
      "r521",
      "r560"
     ],
     "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",
        "terseLabel": "Diluted earnings per common share (in dollars per share)",
        "verboseLabel": "Diluted (in dollars per share)"
       }
      }
     },
     "localname": "EarningsPerShareDiluted",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/EarningsPerShareDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_EarningsPerShareTextBlock": {
     "auth_ref": [
      "r135",
      "r137",
      "r138",
      "r141"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for earnings per share.",
        "label": "Earnings Per Share [Text Block]",
        "terseLabel": "Earnings Per Share"
       }
      }
     },
     "localname": "EarningsPerShareTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/EarningsPerShare"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized": {
     "auth_ref": [
      "r331"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cost not yet recognized for nonvested award under share-based payment arrangement.",
        "label": "Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount",
        "terseLabel": "Compensation cost not yet recognized"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1": {
     "auth_ref": [
      "r331"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.",
        "label": "Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition",
        "terseLabel": "Period for recognition"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_EquityComponentDomain": {
     "auth_ref": [
      "r100",
      "r101",
      "r102",
      "r107",
      "r117",
      "r119",
      "r142",
      "r232",
      "r289",
      "r296",
      "r337",
      "r338",
      "r339",
      "r346",
      "r347",
      "r410",
      "r411",
      "r412",
      "r413",
      "r414",
      "r416",
      "r570",
      "r571",
      "r572"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "EquityComponentDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails",
      "http://www.firstib.com/role/BenefitPlansDetailsTextual",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EstimateOfFairValueFairValueDisclosureMember": {
     "auth_ref": [
      "r405"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measured as an estimate of fair value.",
        "label": "Estimate of Fair Value Measurement [Member]",
        "terseLabel": "Fair Value"
       }
      }
     },
     "localname": "EstimateOfFairValueFairValueDisclosureMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock": {
     "auth_ref": [
      "r397"
     ],
     "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 Measurement Inputs and Valuation Techniques [Table Text Block]",
        "terseLabel": "Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueAssetsMeasuredOnRecurringBasisTextBlock": {
     "auth_ref": [
      "r395",
      "r396"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of assets, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class 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": "Fair Value, Assets Measured on Recurring Basis [Table Text Block]",
        "terseLabel": "Fair Value, Assets Measured on Recurring Basis"
       }
      }
     },
     "localname": "FairValueAssetsMeasuredOnRecurringBasisTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock": {
     "auth_ref": [
      "r398",
      "r402"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset.",
        "label": "Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]",
        "terseLabel": "Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation"
       }
      }
     },
     "localname": "FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueByBalanceSheetGroupingTextBlock": {
     "auth_ref": [
      "r395",
      "r406"
     ],
     "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 [Table Text Block]",
        "terseLabel": "Fair Value, by Balance Sheet Grouping"
       }
      }
     },
     "localname": "FairValueByBalanceSheetGroupingTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueByFairValueHierarchyLevelAxis": {
     "auth_ref": [
      "r307",
      "r308",
      "r309",
      "r310",
      "r311",
      "r312",
      "r313",
      "r315",
      "r396",
      "r442",
      "r443",
      "r444"
     ],
     "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 Hierarchy and NAV [Axis]",
        "terseLabel": "Fair Value Hierarchy and NAV [Axis]"
       }
      }
     },
     "localname": "FairValueByFairValueHierarchyLevelAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByMeasurementBasisAxis": {
     "auth_ref": [
      "r395",
      "r403"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by measurement basis.",
        "label": "Measurement Basis [Axis]",
        "terseLabel": "Measurement Basis [Axis]"
       }
      }
     },
     "localname": "FairValueByMeasurementBasisAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "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 Measurement [Domain]",
        "terseLabel": "Fair Value Measurement [Domain]"
       }
      }
     },
     "localname": "FairValueDisclosureItemAmountsDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueDisclosuresAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Fair Value Disclosures [Abstract]",
        "terseLabel": "Fair Value Disclosures [Abstract]"
       }
      }
     },
     "localname": "FairValueDisclosuresAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueDisclosuresTextBlock": {
     "auth_ref": [
      "r401"
     ],
     "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 of Financial Instruments"
       }
      }
     },
     "localname": "FairValueDisclosuresTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstruments"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueInputsLevel1Member": {
     "auth_ref": [
      "r307",
      "r308",
      "r313",
      "r315",
      "r396",
      "r442"
     ],
     "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, Level 1 [Member]",
        "terseLabel": "Quoted\u00a0Prices in\u00a0Active Markets\u00a0for Identical Assets (Level\u00a01)"
       }
      }
     },
     "localname": "FairValueInputsLevel1Member",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueInputsLevel2Member": {
     "auth_ref": [
      "r307",
      "r308",
      "r313",
      "r315",
      "r396",
      "r443"
     ],
     "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, Level 2 [Member]",
        "terseLabel": "Significant Other Observable Inputs (Level\u00a02)"
       }
      }
     },
     "localname": "FairValueInputsLevel2Member",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueInputsLevel3Member": {
     "auth_ref": [
      "r307",
      "r308",
      "r309",
      "r310",
      "r311",
      "r312",
      "r313",
      "r315",
      "r396",
      "r444"
     ],
     "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, Level 3 [Member]",
        "terseLabel": "Significant Unobservable Inputs (Level\u00a03)"
       }
      }
     },
     "localname": "FairValueInputsLevel3Member",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations": {
     "auth_ref": [
      "r395",
      "r396"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.",
        "label": "Subordinated Debt Obligations, Fair Value Disclosure",
        "terseLabel": "Subordinated debt, Fair Value"
       }
      }
     },
     "localname": "FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1": {
     "auth_ref": [
      "r399"
     ],
     "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 Earnings",
        "verboseLabel": "Included in net income"
       }
      }
     },
     "localname": "FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchasesSalesIssuancesSettlements": {
     "auth_ref": [
      "r400"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of purchases, (sales), issuances and (settlements) 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, Purchases, (Sales), Issuances, (Settlements)",
        "terseLabel": "Additions"
       }
      }
     },
     "localname": "FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchasesSalesIssuancesSettlements",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue": {
     "auth_ref": [
      "r398"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FairValueMeasurementsFairValueHierarchyDomain": {
     "auth_ref": [
      "r307",
      "r308",
      "r309",
      "r310",
      "r311",
      "r312",
      "r313",
      "r315",
      "r442",
      "r443",
      "r444"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Categories used to prioritize the inputs to valuation techniques to measure fair value.",
        "label": "Fair Value Hierarchy and NAV [Domain]",
        "terseLabel": "Fair Value Hierarchy and NAV [Domain]"
       }
      }
     },
     "localname": "FairValueMeasurementsFairValueHierarchyDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FederalDepositInsuranceCorporationPremiumExpense": {
     "auth_ref": [
      "r531"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 7.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of expense for Federal Deposit Insurance Corporation (FDIC) insurance.",
        "label": "Federal Deposit Insurance Corporation Premium Expense",
        "verboseLabel": "Deposit insurance premium"
       }
      }
     },
     "localname": "FederalDepositInsuranceCorporationPremiumExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FederalHomeLoanBankBorrowingsFairValueDisclosure": {
     "auth_ref": [
      "r511"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).",
        "label": "Federal Home Loan Bank Borrowings, Fair Value Disclosure",
        "terseLabel": "Advances from Federal Home Loan Bank, Fair Value"
       }
      }
     },
     "localname": "FederalHomeLoanBankBorrowingsFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FederalHomeLoanBankStock": {
     "auth_ref": [
      "r544"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 6.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).",
        "label": "Federal Home Loan Bank Stock",
        "terseLabel": "FHLB stock, Carrying Amount",
        "verboseLabel": "Federal Home Loan Bank of Indianapolis stock"
       }
      }
     },
     "localname": "FederalHomeLoanBankStock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancialInstrumentAxis": {
     "auth_ref": [
      "r212",
      "r216",
      "r237",
      "r239",
      "r240",
      "r242",
      "r244",
      "r255",
      "r257",
      "r258",
      "r259",
      "r439",
      "r440",
      "r441",
      "r442",
      "r443",
      "r444",
      "r446",
      "r447",
      "r448",
      "r452",
      "r453",
      "r454",
      "r455",
      "r459",
      "r462",
      "r471",
      "r472",
      "r473",
      "r474",
      "r477",
      "r478",
      "r479",
      "r480",
      "r481",
      "r482",
      "r483",
      "r484",
      "r486",
      "r487",
      "r488"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of financial instrument.",
        "label": "Financial Instrument [Axis]",
        "terseLabel": "Financial Instrument [Axis]"
       }
      }
     },
     "localname": "FinancialInstrumentAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails",
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails",
      "http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]",
        "verboseLabel": "Loans:"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment": {
     "auth_ref": [
      "r171"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_LoansAndLeasesReceivableAllowance",
       "weight": 1.0
      }
     },
     "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": "Ending balance: collectively evaluated for impairment"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1": {
     "auth_ref": [
      "r171"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_LoansAndLeasesReceivableAllowance",
       "weight": 1.0
      }
     },
     "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 Impairment",
        "terseLabel": "Ending balance: individually evaluated for impairment"
       }
      }
     },
     "localname": "FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment": {
     "auth_ref": [
      "r172"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_LoansAndLeasesReceivableGrossCarryingAmount",
       "weight": 1.0
      }
     },
     "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": "Ending balance: collectively evaluated for impairment"
       }
      }
     },
     "localname": "FinancingReceivableCollectivelyEvaluatedForImpairment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableCreditQualityIndicatorsTableTextBlock": {
     "auth_ref": [
      "r181",
      "r244"
     ],
     "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": "Financing Receivable Credit Quality Indicators"
       }
      }
     },
     "localname": "FinancingReceivableCreditQualityIndicatorsTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment": {
     "auth_ref": [
      "r172"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_LoansAndLeasesReceivableGrossCarryingAmount",
       "weight": 1.0
      }
     },
     "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": "Ending balance: individually evaluated for impairment"
       }
      }
     },
     "localname": "FinancingReceivableIndividuallyEvaluatedForImpairment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableModificationsNumberOfContracts2": {
     "auth_ref": [
      "r183"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of financing receivables that have been modified by troubled debt restructurings.",
        "label": "Financing Receivable, Modifications, Number of Contracts",
        "terseLabel": "Number of contracts classified as TDRs"
       }
      }
     },
     "localname": "FinancingReceivableModificationsNumberOfContracts2",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "us-gaap_FinancingReceivableModificationsRecordedInvestment": {
     "auth_ref": [
      "r183",
      "r195"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable modified as troubled debt restructuring.",
        "label": "Financing Receivable, Troubled Debt Restructuring",
        "terseLabel": "Financing receivable, troubled debt restructuring"
       }
      }
     },
     "localname": "FinancingReceivableModificationsRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivablePortfolioSegmentAxis": {
     "auth_ref": [
      "r237",
      "r239",
      "r245"
     ],
     "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 [Axis]"
       }
      }
     },
     "localname": "FinancingReceivablePortfolioSegmentAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails",
      "http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "FinancingReceivablePortfolioSegmentDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails",
      "http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing": {
     "auth_ref": [
      "r186",
      "r241",
      "r251"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable 90 days or more past due and still accruing.",
        "label": "Financing Receivable, 90 Days or More Past Due, Still Accruing",
        "terseLabel": "Total\u00a0Loans 90\u00a0Days\u00a0or More\u00a0Past Due\u00a0and Accruing"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis": {
     "auth_ref": [
      "r182",
      "r187",
      "r188",
      "r240",
      "r242",
      "r244",
      "r246",
      "r247",
      "r250",
      "r251"
     ],
     "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": "Class of Financing Receivable [Axis]",
        "terseLabel": "Class of Financing Receivable [Axis]"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "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": "Class of Financing Receivable [Domain]",
        "terseLabel": "Class of Financing Receivable [Domain]"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestmentCurrent": {
     "auth_ref": [
      "r188",
      "r240",
      "r251"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_LoansAndLeasesReceivableGrossCarryingAmount",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable not past due.",
        "label": "Financing Receivable, Not Past Due",
        "terseLabel": "Current"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentCurrent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails"
     ],
     "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, Credit Quality Indicator [Line Items]",
        "terseLabel": "Financing Receivable, Credit Quality Indicator [Line Items]"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FinancingReceivableRecordedInvestmentPastDue": {
     "auth_ref": [
      "r188",
      "r240",
      "r251"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_LoansAndLeasesReceivableGrossCarryingAmount",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of financing receivable past due.",
        "label": "Financing Receivable, Past Due",
        "terseLabel": "Total Past\u00a0Due"
       }
      }
     },
     "localname": "FinancingReceivableRecordedInvestmentPastDue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_FinancingReceivables30To59DaysPastDueMember": {
     "auth_ref": [
      "r251"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financial asset more than 29 days past due but fewer than 60 days past due.",
        "label": "Financial Asset, 30 to 59 Days Past Due [Member]",
        "terseLabel": "30-59 Days Past\u00a0Due"
       }
      }
     },
     "localname": "FinancingReceivables30To59DaysPastDueMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancingReceivables60To89DaysPastDueMember": {
     "auth_ref": [
      "r251"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financial asset more than 59 days past due but fewer than 90 days past due.",
        "label": "Financial Asset, 60 to 89 Days Past Due [Member]",
        "terseLabel": "60-89 Days Past\u00a0Due"
       }
      }
     },
     "localname": "FinancingReceivables60To89DaysPastDueMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember": {
     "auth_ref": [
      "r251"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Financial asset equal to or greater than 90 days past due.",
        "label": "Financial Asset, Equal to or Greater than 90 Days Past Due [Member]",
        "terseLabel": "90\u00a0Days or\u00a0More Past\u00a0Due"
       }
      }
     },
     "localname": "FinancingReceivablesEqualToGreaterThan90DaysPastDueMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FinancingReceivablesPeriodPastDueAxis": {
     "auth_ref": [
      "r240",
      "r251"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by time period financial asset is past due.",
        "label": "Financial Asset, Period Past Due [Axis]",
        "terseLabel": "Financial Asset, Period Past Due [Axis]"
       }
      }
     },
     "localname": "FinancingReceivablesPeriodPastDueAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails"
     ],
     "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": "Financial Asset, Period Past Due [Domain]",
        "terseLabel": "Financial Asset, Period Past Due [Domain]"
       }
      }
     },
     "localname": "FinancingReceivablesPeriodPastDueDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ForwardContractsMember": {
     "auth_ref": [
      "r381"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Contracts negotiated between two parties to purchase and sell a specific quantity of a financial instrument, foreign currency, or commodity at a price specified at origination of the contract, with delivery and settlement at a specified future date.",
        "label": "Forward Contracts [Member]",
        "terseLabel": "Forward contracts"
       }
      }
     },
     "localname": "ForwardContractsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FurnitureAndFixturesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Equipment commonly used in offices and stores that have no permanent connection to the structure of a building or utilities. Examples include, but are not limited to, desks, chairs, tables, and bookcases.",
        "label": "Furniture and Fixtures [Member]",
        "terseLabel": "Furniture and equipment"
       }
      }
     },
     "localname": "FurnitureAndFixturesMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_GainLossOnSaleOfLoansAndLeases": {
     "auth_ref": [
      "r83"
     ],
     "calculation": {
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans and leases that were sold during the reporting period. This element refers to the gain (loss) and not to the cash proceeds of the sales. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.",
        "label": "Gain (Loss) on Sale of Loans and Leases",
        "terseLabel": "Gain on loans sold"
       }
      }
     },
     "localname": "GainLossOnSaleOfLoansAndLeases",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GainLossOnSaleOfOtherLoansAndLeases": {
     "auth_ref": [
      "r83"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_NoninterestIncome",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of other loans and leases that were sold during the reporting period; excludes gains (losses) on sales of consumer and mortgage loans. This element refers to the gain (loss) and not to the cash proceeds of the sales. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.",
        "label": "Gain (Loss) on Sale of Other Loans and Leases",
        "terseLabel": "Gain (loss) on sale of loans"
       }
      }
     },
     "localname": "GainLossOnSaleOfOtherLoansAndLeases",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GainLossOnSalesOfLoansNet": {
     "auth_ref": [
      "r83",
      "r527",
      "r563"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The net gain (loss) resulting from a sale of loans, including adjustments to record loans classified as held-for-sale at the lower-of-cost-or-market and fair value adjustments to loan held for investment purposes.",
        "label": "Gain (Loss) on Sales of Loans, Net",
        "negatedTerseLabel": "Gain on loans sold"
       }
      }
     },
     "localname": "GainLossOnSalesOfLoansNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GainsLossesOnSalesOfOtherRealEstate": {
     "auth_ref": [
      "r530"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 9.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The net gain (loss) resulting from sales and other disposals of other real estate owned, increases (decreases) in the valuation allowance for foreclosed real estate, and write-downs of other real estate owned after acquisition or physical possession.",
        "label": "Gains (Losses) on Sales of Other Real Estate",
        "negatedTerseLabel": "Gain on sale of other real estate owned"
       }
      }
     },
     "localname": "GainsLossesOnSalesOfOtherRealEstate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Goodwill": {
     "auth_ref": [
      "r260",
      "r261",
      "r502"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 9.0,
       "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",
        "verboseLabel": "Goodwill"
       }
      }
     },
     "localname": "Goodwill",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/GoodwillDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Goodwill and Intangible Assets Disclosure [Abstract]",
        "terseLabel": "Goodwill and Intangible Assets Disclosure [Abstract]"
       }
      }
     },
     "localname": "GoodwillAndIntangibleAssetsDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock": {
     "auth_ref": [
      "r262"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for goodwill and intangible assets.",
        "label": "Goodwill and Intangible Assets Disclosure [Text Block]",
        "terseLabel": "Goodwill"
       }
      }
     },
     "localname": "GoodwillAndIntangibleAssetsDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/Goodwill"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_HedgingDesignationAxis": {
     "auth_ref": [
      "r367",
      "r385"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by designation of purpose of derivative instrument.",
        "label": "Hedging Designation [Axis]",
        "terseLabel": "Hedging Designation [Axis]"
       }
      }
     },
     "localname": "HedgingDesignationAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "HedgingDesignationDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_HeldToMaturitySecurities": {
     "auth_ref": [
      "r196",
      "r206",
      "r508"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 12.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      },
      "http://www.firstib.com/role/SecuritiesDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in debt security measured at amortized cost (held-to-maturity).",
        "label": "Debt Securities, Held-to-maturity",
        "terseLabel": "Securities held-to-maturity, at amortized cost (fair value of $69,152 and $62,560 in 2020 and 2019, respectively)",
        "totalLabel": "Held-to-maturity securities, amortized cost",
        "verboseLabel": "Debt Securities, Held-to-maturity"
       }
      }
     },
     "localname": "HeldToMaturitySecurities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]",
        "terseLabel": "Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain": {
     "auth_ref": [
      "r208",
      "r214"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_HeldToMaturitySecurities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).",
        "label": "Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain",
        "terseLabel": "Held-to-maturity securities, Gross Unrealized Gains"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss": {
     "auth_ref": [
      "r209",
      "r215"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_HeldToMaturitySecurities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).",
        "label": "Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss",
        "negatedTerseLabel": "Held-to-maturity securities, Gross Unrealized Losses"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss": {
     "auth_ref": [
      "r221",
      "r222"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.",
        "label": "Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss",
        "negatedTerseLabel": "Held-to-maturity securities, 12 Months or Longer, Unrealized Losses"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss": {
     "auth_ref": [
      "r221"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.",
        "label": "Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss",
        "negatedTotalLabel": "Held-to-maturity securities, Total, Unrealized Losses"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue": {
     "auth_ref": [
      "r220"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.",
        "label": "Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value",
        "totalLabel": "Held-to-maturity securities, Total, Fair Value"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss": {
     "auth_ref": [
      "r221",
      "r222"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for less than 12 months.",
        "label": "Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss",
        "negatedTerseLabel": "Held-to-maturity securities, Less Than 12 Months, Unrealized Losses"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue": {
     "auth_ref": [
      "r222"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for less than 12 months.",
        "label": "Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value",
        "terseLabel": "Held-to-maturity securities, Less Than 12 Months, Fair Value"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue": {
     "auth_ref": [
      "r222"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for 12 months or longer.",
        "label": "Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value",
        "terseLabel": "Held-to-maturity securities, 12 Months or Longer, Fair Value"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue": {
     "auth_ref": [
      "r211",
      "r217",
      "r539",
      "r541"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).",
        "label": "Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10",
        "terseLabel": "Held-to-maturity securities, After ten years"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date, maturing in sixth through tenth rolling fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value",
        "terseLabel": "Held-to-maturity securities, Five to ten years"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date, maturing in second through fifth rolling fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value",
        "terseLabel": "Held-to-maturity securities, One to five years"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis": {
     "auth_ref": [
      "r210",
      "r540"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amortized cost of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date.",
        "label": "Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Amortized Cost",
        "totalLabel": "Held-to-maturity securities, Amortized Cost"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue": {
     "auth_ref": [
      "r210",
      "r218",
      "r540",
      "r542"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date.",
        "label": "Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Fair Value",
        "totalLabel": "Held-to-maturity securities, Fair Value"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesFairValue": {
     "auth_ref": [
      "r207",
      "r213",
      "r508"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_HeldToMaturitySecurities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of investment in debt security measured at amortized cost (held-to-maturity).",
        "label": "Debt Securities, Held-to-maturity, Fair Value",
        "terseLabel": "Held-to-maturity, at fair value"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldToMaturitySecuritiesTextBlock": {
     "auth_ref": [
      "r212",
      "r216",
      "r218"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of information about investment in debt security measured at amortized cost (held-to-maturity).",
        "label": "Debt Securities, Held-to-maturity [Table Text Block]",
        "terseLabel": "Held-to-maturity Securities"
       }
      }
     },
     "localname": "HeldToMaturitySecuritiesTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date, maturing after rolling tenth fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost",
        "terseLabel": "Held-to-maturity securities, After ten years"
       }
      }
     },
     "localname": "HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldtomaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCost": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date, maturing in sixth through tenth rolling fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Amortized Cost",
        "terseLabel": "Held-to-maturity securities, Five to ten years"
       }
      }
     },
     "localname": "HeldtomaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCost",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HeldtomaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCost": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date, maturing in second through fifth rolling fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.",
        "label": "Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost",
        "terseLabel": "Held-to-maturity securities, One to five years"
       }
      }
     },
     "localname": "HeldtomaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCost",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_HomeEquityLoanMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loan based on the equity of the borrower's residential property in which the borrower receives the loan amount upfront. Excludes home equity lines of credit.",
        "label": "Home Equity Loan [Member]",
        "terseLabel": "Home equity"
       }
      }
     },
     "localname": "HomeEquityLoanMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment": {
     "auth_ref": [
      "r177",
      "r180"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "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",
        "totalLabel": "Impaired Financing Receivable, Average Recorded Investment"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableAverageRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod": {
     "auth_ref": [
      "r178"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.",
        "label": "Impaired Financing Receivable, Interest Income, Accrual Method",
        "totalLabel": "Impaired Financing Receivable, Interest Income, Accrual Method"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableInterestIncomeAccrualMethod",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableRecordedInvestment": {
     "auth_ref": [
      "r174"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "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",
        "totalLabel": "Impaired Financing Receivable, Recorded Investment"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableRelatedAllowance": {
     "auth_ref": [
      "r175"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of allowance for credit losses related to recorded investment.",
        "label": "Impaired Financing Receivable, Related Allowance",
        "totalLabel": "Impaired Financing Receivable, Related Allowance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableRelatedAllowance",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance": {
     "auth_ref": [
      "r176"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "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",
        "totalLabel": "Impaired Financing Receivable, Unpaid Principal Balance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableUnpaidPrincipalBalance",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment": {
     "auth_ref": [
      "r177",
      "r180"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment",
       "weight": 1.0
      }
     },
     "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": "Loans without a specific valuation allowance - Average Balance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod": {
     "auth_ref": [
      "r178"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of interest income, recognized on accrual basis, on financing receivables that are recognized as impaired, for which there is no related allowance for credit losses.",
        "label": "Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method",
        "terseLabel": "Loans without a specific valuation allowance - Interest Income"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment": {
     "auth_ref": [
      "r174"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_ImpairedFinancingReceivableRecordedInvestment",
       "weight": 1.0
      }
     },
     "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": "Loans without a specific valuation allowance - Recorded Balance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance": {
     "auth_ref": [
      "r176"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance",
       "weight": 1.0
      }
     },
     "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": "Loans without a specific valuation allowance - Unpaid Principal Balance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment": {
     "auth_ref": [
      "r177",
      "r180"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment",
       "weight": 1.0
      }
     },
     "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": "Loans with a specific valuation allowance - Average Balance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod": {
     "auth_ref": [
      "r178"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired.",
        "label": "Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method",
        "terseLabel": "Loans with a specific valuation allowance - Interest Income"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment": {
     "auth_ref": [
      "r174"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_ImpairedFinancingReceivableRecordedInvestment",
       "weight": 1.0
      }
     },
     "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": "Impaired loans"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance": {
     "auth_ref": [
      "r176"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansImpairedLoansDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance",
       "weight": 1.0
      }
     },
     "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": "Loans with a specific valuation allowance - Unpaid Principal Balance"
       }
      }
     },
     "localname": "ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairedFinancingReceivablesTableTextBlock": {
     "auth_ref": [
      "r179"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of impaired financing receivables.",
        "label": "Impaired Financing Receivables [Table Text Block]",
        "terseLabel": "Impaired Financing Receivables"
       }
      }
     },
     "localname": "ImpairedFinancingReceivablesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ImpairmentOfInvestments": {
     "auth_ref": [
      "r198"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 7.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.",
        "label": "Other than Temporary Impairment Losses, Investments",
        "terseLabel": "Loss on other-than-temporary impairment of securities"
       }
      }
     },
     "localname": "ImpairmentOfInvestments",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments": {
     "auth_ref": [
      "r97",
      "r151",
      "r153",
      "r156",
      "r159",
      "r161"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_NetIncomeLoss",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.",
        "label": "Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest",
        "totalLabel": "Income Before Income Taxes"
       }
      }
     },
     "localname": "IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeStatementAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Income Statement [Abstract]",
        "terseLabel": "Income Statement [Abstract]"
       }
      }
     },
     "localname": "IncomeStatementAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeStatementLocationAxis": {
     "auth_ref": [
      "r266"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by location in the income statement.",
        "label": "Income Statement Location [Axis]",
        "terseLabel": "Income Statement Location [Axis]"
       }
      }
     },
     "localname": "IncomeStatementLocationAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "IncomeStatementLocationDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_IncomeTaxExpenseBenefit": {
     "auth_ref": [
      "r94",
      "r118",
      "r119",
      "r150",
      "r343",
      "r351",
      "r353",
      "r562"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_NetIncomeLoss",
       "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)",
        "verboseLabel": "Income Tax (Benefit) Provision"
       }
      }
     },
     "localname": "IncomeTaxExpenseBenefit",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeTaxesPaidNet": {
     "auth_ref": [
      "r87"
     ],
     "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": "Income Taxes Paid, Net"
       }
      }
     },
     "localname": "IncomeTaxesPaidNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities": {
     "auth_ref": [
      "r82"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase (decrease) in accrued expenses, and obligations classified as other.",
        "label": "Increase (Decrease) in Accrued Liabilities and Other Operating Liabilities",
        "verboseLabel": "Net change in accrued expenses and other liabilities"
       }
      }
     },
     "localname": "IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInDeposits": {
     "auth_ref": [
      "r86",
      "r536"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 2.0,
       "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",
        "verboseLabel": "Net increase in deposits"
       }
      }
     },
     "localname": "IncreaseDecreaseInDeposits",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInDerivativeAssets": {
     "auth_ref": [
      "r82"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The increase (decrease) during the period in the carrying value of derivative instruments reported as assets that are due to be disposed of within one year (or the normal operating cycle, if longer).",
        "label": "Increase (Decrease) in Derivative Assets",
        "terseLabel": "Cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets",
        "verboseLabel": "Fair Value"
       }
      }
     },
     "localname": "IncreaseDecreaseInDerivativeAssets",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInLoansHeldForSale": {
     "auth_ref": [
      "r77",
      "r82"
     ],
     "calculation": {
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax",
       "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",
        "terseLabel": "(Loss) gain resulting from the change in fair value of loans held-for-sale"
       }
      }
     },
     "localname": "IncreaseDecreaseInLoansHeldForSale",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInOtherOperatingAssets": {
     "auth_ref": [
      "r82"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 6.0,
       "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": "Net change in accrued income and other assets"
       }
      }
     },
     "localname": "IncreaseDecreaseInOtherOperatingAssets",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements": {
     "auth_ref": [
      "r126",
      "r127",
      "r128",
      "r134"
     ],
     "calculation": {
      "http://www.firstib.com/role/EarningsPerShareDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment",
       "weight": 1.0
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.",
        "label": "Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements",
        "verboseLabel": "Dilutive effect of equity compensation (in shares)"
       }
      }
     },
     "localname": "IncrementalCommonSharesAttributableToShareBasedPaymentArrangements",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/EarningsPerShareDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_InformationTechnologyAndDataProcessing": {
     "auth_ref": [
      "r64"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 4.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of expenses incurred in the period for information technology and data processing products and services.",
        "label": "Information Technology and Data Processing",
        "verboseLabel": "Data processing"
       }
      }
     },
     "localname": "InformationTechnologyAndDataProcessing",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestAndDividendIncomeOperating": {
     "auth_ref": [
      "r523"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 1.0,
       "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",
        "totalLabel": "Total interest income"
       }
      }
     },
     "localname": "InterestAndDividendIncomeOperating",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestAndDividendIncomeOperatingAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Interest and Dividend Income, Operating [Abstract]",
        "verboseLabel": "Interest Income"
       }
      }
     },
     "localname": "InterestAndDividendIncomeOperatingAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_InterestAndFeeIncomeLoansAndLeases": {
     "auth_ref": [
      "r522"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 1.0,
       "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",
        "verboseLabel": "Loans"
       }
      }
     },
     "localname": "InterestAndFeeIncomeLoansAndLeases",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestBearingDepositLiabilities": {
     "auth_ref": [
      "r510"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "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",
        "verboseLabel": "Interest-bearing deposits"
       }
      }
     },
     "localname": "InterestBearingDepositLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestBearingDepositsInBanks": {
     "auth_ref": [
      "r500",
      "r514"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "parentTag": "us-gaap_CashAndCashEquivalentsAtCarryingValue",
       "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 and Other Financial Institutions",
        "verboseLabel": "Interest-bearing deposits"
       }
      }
     },
     "localname": "InterestBearingDepositsInBanks",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestExpense": {
     "auth_ref": [
      "r57",
      "r148",
      "r417",
      "r420",
      "r535"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 2.0,
       "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",
        "terseLabel": "Interest expense",
        "totalLabel": "Total interest expense"
       }
      }
     },
     "localname": "InterestExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestExpenseAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Interest Expense [Abstract]",
        "verboseLabel": "Interest Expense"
       }
      }
     },
     "localname": "InterestExpenseAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_InterestExpenseBorrowings": {
     "auth_ref": [
      "r534"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_InterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate amount of interest expense on all borrowings.",
        "label": "Interest Expense, Borrowings",
        "verboseLabel": "Other borrowed funds"
       }
      }
     },
     "localname": "InterestExpenseBorrowings",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestExpenseDeposits": {
     "auth_ref": [
      "r533"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 1.0,
       "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",
        "verboseLabel": "Deposits"
       }
      }
     },
     "localname": "InterestExpenseDeposits",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestExpenseMember": {
     "auth_ref": [
      "r383"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Primary financial statement caption encompassing interest expense.",
        "label": "Interest Expense [Member]",
        "terseLabel": "Total interest expense"
       }
      }
     },
     "localname": "InterestExpenseMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss": {
     "auth_ref": [
      "r526"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments",
       "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 Income After Provision for Loan Losses"
       }
      }
     },
     "localname": "InterestIncomeExpenseAfterProvisionForLoanLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestIncomeExpenseNet": {
     "auth_ref": [
      "r524"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 1.0,
       "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 Income"
       }
      }
     },
     "localname": "InterestIncomeExpenseNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestIncomeMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Primary financial statement caption in which reported facts about interest income have been included.",
        "label": "Interest Income [Member]",
        "terseLabel": "Total interest income"
       }
      }
     },
     "localname": "InterestIncomeMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InterestIncomeOther": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 4.0,
       "parentTag": "us-gaap_InterestAndDividendIncomeOperating",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of interest income earned from interest bearing assets classified as other.",
        "label": "Interest Income, Other",
        "terseLabel": "Other earning assets"
       }
      }
     },
     "localname": "InterestIncomeOther",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestIncomeSecuritiesTaxExempt": {
     "auth_ref": [
      "r532"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_InterestAndDividendIncomeOperating",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities exempt from state, federal and other income tax.",
        "label": "Interest Income, Securities, Operating, Tax Exempt",
        "verboseLabel": "Securities \u2013 non-taxable"
       }
      }
     },
     "localname": "InterestIncomeSecuritiesTaxExempt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestIncomeSecuritiesTaxable": {
     "auth_ref": [
      "r532"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_InterestAndDividendIncomeOperating",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities subject to state, federal and other income tax.",
        "label": "Interest Income, Securities, Operating, Taxable",
        "verboseLabel": "Securities \u2013 taxable"
       }
      }
     },
     "localname": "InterestIncomeSecuritiesTaxable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestPaidNet": {
     "auth_ref": [
      "r76",
      "r80",
      "r87"
     ],
     "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, Excluding Capitalized Interest, Operating Activities",
        "verboseLabel": "Cash paid during the period for interest"
       }
      }
     },
     "localname": "InterestPaidNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestPayableCurrentAndNoncurrent": {
     "auth_ref": [
      "r512",
      "r556"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 4.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of interest payable on debt, including, but not limited to, trade payables.",
        "label": "Interest Payable",
        "terseLabel": "Accrued interest payable",
        "verboseLabel": "Accrued interest payable, Carrying Amount"
       }
      }
     },
     "localname": "InterestPayableCurrentAndNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestRateLockCommitmentsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Commitments to extend credit where the interest rate is locked in advance of funds being disbursed for a specified period of time.",
        "label": "Interest Rate Lock Commitments [Member]",
        "terseLabel": "IRLCs",
        "verboseLabel": "Interest\u00a0Rate Lock Commitments"
       }
      }
     },
     "localname": "InterestRateLockCommitmentsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InterestRateSwapMember": {
     "auth_ref": [
      "r382"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Forward based contracts in which two parties agree to swap periodic payments that are fixed at the outset of the swap contract with variable payments based on a market interest rate (index rate) over a specified period.",
        "label": "Interest Rate Swap [Member]",
        "terseLabel": "Interest rate swaps"
       }
      }
     },
     "localname": "InterestRateSwapMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/LoansCategoriesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InterestReceivable": {
     "auth_ref": [
      "r27"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 5.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "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",
        "verboseLabel": "Accrued interest receivable, Carrying Amount"
       }
      }
     },
     "localname": "InterestReceivable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InternalCreditAssessmentAxis": {
     "auth_ref": [
      "r181",
      "r244",
      "r249",
      "r250",
      "r281",
      "r386"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by entity-defined rating.",
        "label": "Internal Credit Assessment [Axis]",
        "terseLabel": "Internal Credit Assessment [Axis]"
       }
      }
     },
     "localname": "InternalCreditAssessmentAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "InternalCreditAssessmentDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Investments, Debt and Equity Securities [Abstract]",
        "terseLabel": "Investments, Debt and Equity Securities [Abstract]"
       }
      }
     },
     "localname": "InvestmentsDebtAndEquitySecuritiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock": {
     "auth_ref": [
      "r226",
      "r499",
      "r543",
      "r583"
     ],
     "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": "Securities"
       }
      }
     },
     "localname": "InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/Securities"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LaborAndRelatedExpense": {
     "auth_ref": [
      "r62"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of expense for salary, wage, profit sharing; incentive and equity-based compensation; and other employee benefit.",
        "label": "Labor and Related Expense",
        "verboseLabel": "Salaries and employee benefits"
       }
      }
     },
     "localname": "LaborAndRelatedExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LandMember": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Part of earth's surface not covered by water.",
        "label": "Land [Member]",
        "terseLabel": "Land"
       }
      }
     },
     "localname": "LandMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LeaseCostTableTextBlock": {
     "auth_ref": [
      "r431"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of lessee's lease cost. Includes, but is not limited to, interest expense for finance lease, amortization of right-of-use asset for finance lease, operating lease cost, short-term lease cost, variable lease cost and sublease income.",
        "label": "Lease, Cost [Table Text Block]",
        "terseLabel": "Lease, Cost"
       }
      }
     },
     "localname": "LeaseCostTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LeasesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Leases [Abstract]",
        "terseLabel": "Leases [Abstract]"
       }
      }
     },
     "localname": "LeasesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock": {
     "auth_ref": [
      "r432"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of undiscounted cash flows of lessee's operating lease liability. Includes, but is not limited to, reconciliation of undiscounted cash flows to operating lease liability recognized in statement of financial position.",
        "label": "Lessee, Operating Lease, Liability, Maturity [Table Text Block]",
        "terseLabel": "Lessee, Operating Lease, Liability, Maturity"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityMaturityTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue": {
     "auth_ref": [
      "r432"
     ],
     "calculation": {
      "http://www.firstib.com/role/LeasesMaturityDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.firstib.com/role/LeasesMaturityDetails_1": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payment for operating lease.",
        "label": "Lessee, Operating Lease, Liability, to be Paid",
        "totalLabel": "Total lease payments"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesMaturityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterRollingYearFive": {
     "auth_ref": [
      "r432"
     ],
     "calculation": {
      "http://www.firstib.com/role/LeasesMaturityDetails": {
       "order": 6.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payments for operating lease, due after fifth rolling twelve months following latest statement of financial position date. For interim and annual periods when interim periods are reported on rolling approach, from latest statement of financial position date.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due after Rolling Year Five",
        "terseLabel": "Thereafter"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueAfterRollingYearFive",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesMaturityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive": {
     "auth_ref": [
      "r432"
     ],
     "calculation": {
      "http://www.firstib.com/role/LeasesMaturityDetails": {
       "order": 5.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payments for operating lease, due in fifth rolling twelve months following latest statement of financial position date. For interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Five",
        "terseLabel": "2025"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesMaturityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour": {
     "auth_ref": [
      "r432"
     ],
     "calculation": {
      "http://www.firstib.com/role/LeasesMaturityDetails": {
       "order": 4.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payments for operating lease, due in fourth rolling twelve months following latest statement of financial position date. For interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Four",
        "terseLabel": "2024"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesMaturityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree": {
     "auth_ref": [
      "r432"
     ],
     "calculation": {
      "http://www.firstib.com/role/LeasesMaturityDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payments for operating lease, due in third rolling twelve months following latest statement of financial position date. For interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Three",
        "terseLabel": "2023"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesMaturityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo": {
     "auth_ref": [
      "r432"
     ],
     "calculation": {
      "http://www.firstib.com/role/LeasesMaturityDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payments for operating lease, due in second rolling twelve months following latest statement of financial position date. For interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Two",
        "terseLabel": "2022"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesMaturityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths": {
     "auth_ref": [
      "r432"
     ],
     "calculation": {
      "http://www.firstib.com/role/LeasesMaturityDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payments for operating lease, due in next rolling twelve months following latest statement of financial position date. For interim and annual periods when interim periods are reported on a rolling approach, from latest statement of financial position date.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due Next Rolling Twelve Months",
        "terseLabel": "2021"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesMaturityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount": {
     "auth_ref": [
      "r432"
     ],
     "calculation": {
      "http://www.firstib.com/role/LeasesMaturityDetails_1": {
       "order": 1.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating lease.",
        "label": "Lessee, Operating Lease, Liability, Undiscounted Excess Amount",
        "negatedTerseLabel": "Less: imputed interest"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityUndiscountedExcessAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesMaturityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeasesTextBlock": {
     "auth_ref": [
      "r434"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for operating leases of lessee. Includes, but is not limited to, description of operating lease and maturity analysis of operating lease liability.",
        "label": "Lessee, Operating Leases [Text Block]",
        "terseLabel": "Leases"
       }
      }
     },
     "localname": "LesseeOperatingLeasesTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/Leases"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_Liabilities": {
     "auth_ref": [
      "r20",
      "r93",
      "r155",
      "r228",
      "r358",
      "r361",
      "r362",
      "r408"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 1.0,
       "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LiabilitiesAndStockholdersEquity": {
     "auth_ref": [
      "r16",
      "r93",
      "r228",
      "r408",
      "r507",
      "r553"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "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 Equity",
        "totalLabel": "Total liabilities and shareholders\u2019 equity"
       }
      }
     },
     "localname": "LiabilitiesAndStockholdersEquity",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LiabilitiesAndStockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Liabilities and Equity [Abstract]",
        "verboseLabel": "Liabilities and Shareholders\u2019 Equity"
       }
      }
     },
     "localname": "LiabilitiesAndStockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LiabilityMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "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": "Liability [Member]",
        "terseLabel": "Liability"
       }
      }
     },
     "localname": "LiabilityMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LoanProcessingFee": {
     "auth_ref": [],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 5.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Expenses paid for obtaining loans which includes expenses such as application and origination fees.",
        "label": "Loan Processing Fee",
        "verboseLabel": "Loan expenses"
       }
      }
     },
     "localname": "LoanProcessingFee",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoansAndLeasesReceivableAllowance": {
     "auth_ref": [
      "r167",
      "r171",
      "r190",
      "r194"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "parentTag": "us-gaap_LoansAndLeasesReceivableNetReportedAmount",
       "weight": -1.0
      },
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.",
        "label": "Loans and Leases Receivable, Allowance",
        "negatedLabel": "Allowance for loan losses",
        "negatedTerseLabel": "Allowance for loan losses",
        "periodEndLabel": "Balance, end of period",
        "periodStartLabel": "Balance, beginning of period",
        "totalLabel": "Ending balance"
       }
      }
     },
     "localname": "LoansAndLeasesReceivableAllowance",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoansAndLeasesReceivableGrossCarryingAmount": {
     "auth_ref": [
      "r166"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansCategoriesDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome",
       "weight": 1.0
      },
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.",
        "label": "Loans and Leases Receivable, Gross",
        "terseLabel": "Total Loans Receivable",
        "totalLabel": "Total Loans Receivable",
        "verboseLabel": "Total commercial loans"
       }
      }
     },
     "localname": "LoansAndLeasesReceivableGrossCarryingAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome": {
     "auth_ref": [
      "r166",
      "r185"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 1.0,
       "parentTag": "us-gaap_LoansAndLeasesReceivableNetReportedAmount",
       "weight": 1.0
      },
      "http://www.firstib.com/role/LoansCategoriesDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.",
        "label": "Loans and Leases Receivable, Net of Deferred Income",
        "totalLabel": "Total loans",
        "verboseLabel": "Loans"
       }
      }
     },
     "localname": "LoansAndLeasesReceivableNetOfDeferredIncome",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/LoansCategoriesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoansAndLeasesReceivableNetReportedAmount": {
     "auth_ref": [
      "r166",
      "r515"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 4.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.",
        "label": "Loans and Leases Receivable, Net Amount",
        "terseLabel": "Loans receivable",
        "totalLabel": "Net loans"
       }
      }
     },
     "localname": "LoansAndLeasesReceivableNetReportedAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/LoansCategoriesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoansHeldForSaleFairValueDisclosure": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.",
        "label": "Loans Held-for-sale, Fair Value Disclosure",
        "netLabel": "Loans held for sale, Fair Value",
        "terseLabel": "Loans held-for-sale (mandatory pricing agreements)",
        "verboseLabel": "Loans held-for-sale, at fair value"
       }
      }
     },
     "localname": "LoansHeldForSaleFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoansMember": {
     "auth_ref": [
      "r191"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "When a lender gives money or property over other debt securities sold by the issuer. In the event the issuer goes bankrupt, senior debt holders receive priority for [must receive] repayment [prior] relative to junior and unsecured (general) creditors.",
        "label": "Loans [Member]",
        "terseLabel": "Loans"
       }
      }
     },
     "localname": "LoansMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsCarryingAmountandAdjustmentDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock": {
     "auth_ref": [
      "r191"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/Loans"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LoansReceivableFairValueDisclosure": {
     "auth_ref": [
      "r191"
     ],
     "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 receivable, fair value"
       }
      }
     },
     "localname": "LoansReceivableFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LoansReceivableHeldForSaleNetNotPartOfDisposalGroup": {
     "auth_ref": [
      "r166",
      "r584"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 3.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.",
        "label": "Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance",
        "verboseLabel": "Loans held-for-sale (includes $38,813 and $56,097 at fair value in 2020 and 2019, respectively)"
       }
      }
     },
     "localname": "LoansReceivableHeldForSaleNetNotPartOfDisposalGroup",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "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 (LIBOR) [Member]",
        "terseLabel": "LIBOR"
       }
      }
     },
     "localname": "LondonInterbankOfferedRateLIBORMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LongTermDebt": {
     "auth_ref": [
      "r8",
      "r283",
      "r506",
      "r550"
     ],
     "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": "Principal"
       }
      }
     },
     "localname": "LongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LongTermDebtTextBlock": {
     "auth_ref": [
      "r285"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for long-term debt.",
        "label": "Long-term Debt [Text Block]",
        "terseLabel": "Subordinated Debt"
       }
      }
     },
     "localname": "LongTermDebtTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebt"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LongtermDebtTypeAxis": {
     "auth_ref": [
      "r22"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of long-term debt.",
        "label": "Long-term Debt, Type [Axis]",
        "terseLabel": "Long-term Debt, Type [Axis]"
       }
      }
     },
     "localname": "LongtermDebtTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LongtermDebtTypeDomain": {
     "auth_ref": [
      "r22",
      "r282"
     ],
     "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": "Long-term Debt, Type [Domain]",
        "terseLabel": "Long-term Debt, Type [Domain]"
       }
      }
     },
     "localname": "LongtermDebtTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LossContingenciesByNatureOfContingencyAxis": {
     "auth_ref": [
      "r271",
      "r272",
      "r273",
      "r274",
      "r275",
      "r276",
      "r277",
      "r279",
      "r280"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of existing condition, situation, or set of circumstances involving uncertainty as to possible loss to an enterprise that will ultimately be resolved when one or more future events occur or fail to occur.",
        "label": "Loss Contingency Nature [Axis]",
        "terseLabel": "Loss Contingency Nature [Axis]"
       }
      }
     },
     "localname": "LossContingenciesByNatureOfContingencyAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LossContingencyNatureDomain": {
     "auth_ref": [
      "r271",
      "r272",
      "r273",
      "r274",
      "r275",
      "r276",
      "r277",
      "r279",
      "r280"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "An existing condition, situation, or set of circumstances involving uncertainty as to possible loss to an enterprise that will ultimately be resolved when one or more future events occur or fail to occur. Resolution of the uncertainty may confirm the incurrence of a loss or impairment of an asset or the incurrence of a liability.",
        "label": "Loss Contingency, Nature [Domain]",
        "terseLabel": "Loss Contingency, Nature [Domain]"
       }
      }
     },
     "localname": "LossContingencyNatureDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MarketingAndAdvertisingExpense": {
     "auth_ref": [
      "r63"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The total expense recognized in the period for promotion, public relations, and brand or product advertising.",
        "label": "Marketing and Advertising Expense",
        "verboseLabel": "Marketing, advertising and promotion"
       }
      }
     },
     "localname": "MarketingAndAdvertisingExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_MeasurementInputExpectedTermMember": {
     "auth_ref": [
      "r397"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measurement input using period financial instrument is expected to be outstanding. Excludes maturity date.",
        "label": "Measurement Input, Expected Term [Member]",
        "terseLabel": "Expected weighted-average loan life"
       }
      }
     },
     "localname": "MeasurementInputExpectedTermMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MeasurementInputPrepaymentRateMember": {
     "auth_ref": [
      "r397"
     ],
     "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]",
        "verboseLabel": "Prepayment speeds"
       }
      }
     },
     "localname": "MeasurementInputPrepaymentRateMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MeasurementInputTypeAxis": {
     "auth_ref": [
      "r397"
     ],
     "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 [Axis]"
       }
      }
     },
     "localname": "MeasurementInputTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "MeasurementInputTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember": {
     "auth_ref": [
      "r199",
      "r307"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt securities collateralized by real estate mortgage loans (mortgages), issued by non-governmental sponsored enterprises.",
        "label": "Mortgage-backed Securities, Issued by Private Enterprises [Member]",
        "terseLabel": "Private label mortgage-backed securities"
       }
      }
     },
     "localname": "MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails",
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember": {
     "auth_ref": [
      "r307"
     ],
     "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 US Government Sponsored Enterprises [Member]",
        "terseLabel": "Agency mortgage-backed securities"
       }
      }
     },
     "localname": "MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails",
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MortgageBankingAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Mortgage Banking [Abstract]",
        "terseLabel": "Mortgage Banking [Abstract]"
       }
      }
     },
     "localname": "MortgageBankingAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_MortgageBankingMember": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Origination or servicing of loan secured by real property.",
        "label": "Mortgage Banking [Member]",
        "terseLabel": "Mortgage banking activities"
       }
      }
     },
     "localname": "MortgageBankingMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MortgageLoansInProcessOfForeclosureAmount": {
     "auth_ref": [
      "r184"
     ],
     "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": "Mortgage loans in process of foreclosure, amount"
       }
      }
     },
     "localname": "MortgageLoansInProcessOfForeclosureAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_MunicipalBondsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Long-term debt securities issued by state, city or local governments or the agencies operated by state, city or local governments.",
        "label": "Municipal Bonds [Member]",
        "terseLabel": "Municipal securities"
       }
      }
     },
     "localname": "MunicipalBondsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/SecuritiesDetails",
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_NetCashProvidedByUsedInFinancingActivities": {
     "auth_ref": [
      "r78"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 3.0,
       "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 provided by financing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInFinancingActivities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Net Cash Provided by (Used in) Financing Activities [Abstract]",
        "verboseLabel": "Financing Activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInFinancingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetCashProvidedByUsedInInvestingActivities": {
     "auth_ref": [
      "r78"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 2.0,
       "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 used in investing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInInvestingActivities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Net Cash Provided by (Used in) Investing Activities [Abstract]",
        "verboseLabel": "Investing Activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInInvestingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetCashProvidedByUsedInOperatingActivities": {
     "auth_ref": [
      "r78",
      "r81",
      "r84"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 1.0,
       "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 used in operating activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInOperatingActivities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Net Cash Provided by (Used in) Operating Activities [Abstract]",
        "verboseLabel": "Operating Activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInOperatingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetIncomeLoss": {
     "auth_ref": [
      "r0",
      "r49",
      "r52",
      "r58",
      "r84",
      "r93",
      "r106",
      "r112",
      "r113",
      "r114",
      "r115",
      "r118",
      "r119",
      "r131",
      "r151",
      "r153",
      "r156",
      "r159",
      "r161",
      "r228",
      "r408",
      "r518",
      "r557"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 5.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      },
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_ComprehensiveIncomeNetOfTax",
       "weight": 1.0
      },
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "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) Attributable to Parent",
        "terseLabel": "Net income",
        "totalLabel": "Net Income",
        "verboseLabel": "Net income"
       }
      }
     },
     "localname": "NetIncomeLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/EarningsPerShareDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Accounting Standards Update and Change in Accounting Principle [Abstract]",
        "terseLabel": "New Accounting Pronouncements and Changes in Accounting Principles [Abstract]"
       }
      }
     },
     "localname": "NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock": {
     "auth_ref": [
      "r104",
      "r105",
      "r108",
      "r109",
      "r120",
      "r121",
      "r122",
      "r233",
      "r234",
      "r300",
      "r301",
      "r302",
      "r303",
      "r340",
      "r348",
      "r349",
      "r350",
      "r495",
      "r496",
      "r497",
      "r574",
      "r575",
      "r576",
      "r577",
      "r579"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.",
        "label": "Accounting Standards Update and Change in Accounting Principle [Text Block]",
        "terseLabel": "Recent Accounting Pronouncements"
       }
      }
     },
     "localname": "NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/RecentAccountingPronouncements"
     ],
     "xbrltype": "textBlockItemType"
    },
    "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable": {
     "auth_ref": [
      "r103",
      "r106",
      "r107",
      "r108",
      "r110",
      "r111",
      "r114",
      "r139",
      "r229",
      "r230",
      "r231",
      "r232",
      "r235",
      "r236",
      "r333",
      "r334",
      "r335",
      "r336",
      "r337",
      "r338",
      "r339",
      "r341",
      "r344",
      "r345",
      "r346",
      "r347",
      "r492",
      "r493",
      "r494",
      "r568",
      "r569",
      "r570",
      "r571",
      "r572",
      "r573",
      "r574",
      "r575",
      "r576",
      "r577",
      "r578",
      "r579"
     ],
     "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": "Accounting Standards Update and Change in Accounting Principle [Table]",
        "terseLabel": "New Accounting Pronouncements or Change in Accounting Principle [Table]"
       }
      }
     },
     "localname": "NewAccountingPronouncementsOrChangeInAccountingPrincipleTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesDetails"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BasisofPresentationPolicies"
     ],
     "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": "Not Designated as Hedging Instrument [Member]",
        "terseLabel": "Derivatives not designated as hedging instruments"
       }
      }
     },
     "localname": "NondesignatedMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_NoninterestBearingDepositLiabilities": {
     "auth_ref": [
      "r510"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 1.0,
       "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",
        "verboseLabel": "Noninterest-bearing deposits"
       }
      }
     },
     "localname": "NoninterestBearingDepositLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NoninterestExpense": {
     "auth_ref": [
      "r531"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Total aggregate amount of all noninterest expense.",
        "label": "Noninterest Expense",
        "totalLabel": "Total noninterest expense"
       }
      }
     },
     "localname": "NoninterestExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NoninterestExpenseAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Noninterest Expense [Abstract]",
        "verboseLabel": "Noninterest Expense"
       }
      }
     },
     "localname": "NoninterestExpenseAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NoninterestIncome": {
     "auth_ref": [
      "r528"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments",
       "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",
        "totalLabel": "Total noninterest income"
       }
      }
     },
     "localname": "NoninterestIncome",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NoninterestIncomeAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Noninterest Income [Abstract]",
        "verboseLabel": "Noninterest Income"
       }
      }
     },
     "localname": "NoninterestIncomeAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NoninterestIncomeOtherOperatingIncome": {
     "auth_ref": [
      "r56",
      "r517",
      "r561"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 2.0,
       "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"
       }
      }
     },
     "localname": "NoninterestIncomeOtherOperatingIncome",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NonperformingFinancingReceivableMember": {
     "auth_ref": [
      "r181",
      "r244"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Category status of financial instruments in which payments are past due in accordance with the terms of the contract. Financial instruments include, but are not limited to, financing receivables, loans, debt, and investments.",
        "label": "Nonperforming Financial Instruments [Member]",
        "terseLabel": "Nonaccrual"
       }
      }
     },
     "localname": "NonperformingFinancingReceivableMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_NonvestedRestrictedStockSharesActivityTableTextBlock": {
     "auth_ref": [
      "r324"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the changes in outstanding nonvested restricted stock shares.",
        "label": "Nonvested Restricted Stock Shares Activity [Table Text Block]",
        "terseLabel": "Nonvested Restricted Stock Shares Activity"
       }
      }
     },
     "localname": "NonvestedRestrictedStockSharesActivityTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_NonvotingCommonStockMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Common stock securities that do not empower a holder to vote on corporate resolutions or the election of directors.",
        "label": "Nonvoting Common Stock [Member]",
        "terseLabel": "Nonvoting Common Stock"
       }
      }
     },
     "localname": "NonvotingCommonStockMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_NotesReceivableGross": {
     "auth_ref": [
      "r243",
      "r250",
      "r251"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, before allowance for credit loss, of financing receivable.",
        "label": "Financing Receivable, before Allowance for Credit Loss",
        "terseLabel": "Loans serviced for others"
       }
      }
     },
     "localname": "NotesReceivableGross",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OccupancyNet": {
     "auth_ref": [
      "r64",
      "r422",
      "r529"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 6.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of net occupancy expense that may include items, such as depreciation of facilities and equipment, lease expenses, property taxes and property and casualty insurance expense.",
        "label": "Occupancy, Net",
        "verboseLabel": "Premises and equipment"
       }
      }
     },
     "localname": "OccupancyNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent": {
     "auth_ref": [
      "r45"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before tax and reclassification adjustments of other comprehensive income (loss) attributable to parent.",
        "label": "OCI, before Reclassifications, before Tax, Attributable to Parent",
        "terseLabel": "Net change in unrealized gain"
       }
      }
     },
     "localname": "OciBeforeReclassificationsBeforeTaxAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseCost": {
     "auth_ref": [
      "r426",
      "r433"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.",
        "label": "Operating Lease, Cost",
        "terseLabel": "Operating lease cost"
       }
      }
     },
     "localname": "OperatingLeaseCost",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesDetails"
     ],
     "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",
        "terseLabel": "Operating lease liabilities"
       }
      }
     },
     "localname": "OperatingLeaseLiability",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesBalanceSheetAmountsDetails"
     ],
     "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": "Operating cash flows from operating leases"
       }
      }
     },
     "localname": "OperatingLeasePayments",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesDetails"
     ],
     "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",
        "terseLabel": "Operating lease right-of-use assets"
       }
      }
     },
     "localname": "OperatingLeaseRightOfUseAsset",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesBalanceSheetAmountsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent": {
     "auth_ref": [
      "r430",
      "r433"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Weighted average discount rate for operating lease calculated at point in time.",
        "label": "Operating Lease, Weighted Average Discount Rate, Percent",
        "terseLabel": "Weighted-average discount rate"
       }
      }
     },
     "localname": "OperatingLeaseWeightedAverageDiscountRatePercent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesBalanceSheetAmountsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1": {
     "auth_ref": [
      "r429",
      "r433"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.",
        "label": "Operating Lease, Weighted Average Remaining Lease Term",
        "terseLabel": "Weighted-average remaining lease term (years)"
       }
      }
     },
     "localname": "OperatingLeaseWeightedAverageRemainingLeaseTerm1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LeasesBalanceSheetAmountsDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Organization, Consolidation and Presentation of Financial Statements [Abstract]",
        "terseLabel": "Organization, Consolidation and Presentation of Financial Statements [Abstract]"
       }
      }
     },
     "localname": "OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock": {
     "auth_ref": [
      "r1",
      "r363"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.",
        "label": "Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]",
        "terseLabel": "Basis of Presentation"
       }
      }
     },
     "localname": "OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BasisofPresentation"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_OtherAssets": {
     "auth_ref": [
      "r5",
      "r503",
      "r548"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 11.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of assets classified as other.",
        "label": "Other Assets",
        "verboseLabel": "Accrued income and other assets"
       }
      }
     },
     "localname": "OtherAssets",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherCommitment": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.",
        "label": "Other Commitment",
        "terseLabel": "Construction related contract commitment"
       }
      }
     },
     "localname": "OtherCommitment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRiskDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherCommitmentsAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of other commitment.",
        "label": "Other Commitments [Axis]",
        "terseLabel": "Other Commitments [Axis]"
       }
      }
     },
     "localname": "OtherCommitmentsAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRiskDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OtherCommitmentsDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Other future obligation.",
        "label": "Other Commitments [Domain]",
        "terseLabel": "Other Commitments [Domain]"
       }
      }
     },
     "localname": "OtherCommitmentsDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRiskDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OtherCommitmentsLineItems": {
     "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": "Other Commitments [Line Items]",
        "terseLabel": "Other Commitments [Line Items]"
       }
      }
     },
     "localname": "OtherCommitmentsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRiskDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OtherCommitmentsTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about obligations resulting from other commitments.",
        "label": "Other Commitments [Table]",
        "terseLabel": "Other Commitments [Table]"
       }
      }
     },
     "localname": "OtherCommitmentsTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CommitmentsandCreditRiskDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax": {
     "auth_ref": [
      "r38",
      "r39",
      "r42"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossBeforeTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, before tax and after adjustment, of 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) and unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale.",
        "label": "OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, before Tax",
        "verboseLabel": "Net unrealized holding (losses) gains on securities available-for-sale recorded within other comprehensive (loss) income before income tax"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossBeforeTax": {
     "auth_ref": [
      "r59",
      "r227",
      "r410",
      "r415",
      "r416",
      "r519",
      "r558"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited": {
       "order": 2.0,
       "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",
        "totalLabel": "Other comprehensive (loss) income before income tax"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent": {
     "auth_ref": [
      "r355",
      "r356",
      "r359"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before tax of other comprehensive income (loss) attributable to parent entity.",
        "label": "Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent",
        "terseLabel": "Accumulated other comprehensive loss before income tax"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax": {
     "auth_ref": [
      "r43"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, before reclassification, of tax expense (benefit) for gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.",
        "label": "Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax",
        "terseLabel": "Amount of Loss Recognized in Other Comprehensive Income"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsTax": {
     "auth_ref": [
      "r37",
      "r42",
      "r375",
      "r390"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, before adjustments, of tax expense (benefit) for gain (loss) from increase (decrease) in value of excluded component of derivative designated and qualifying as hedge. Adjustments include, but are not limited to, reclassifications for sale and settlement, and amounts recognized under systematic and rational method.",
        "label": "Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), before Adjustments, Tax",
        "terseLabel": "Gain (loss) recognized on the condensed consolidated statements of income"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossNetOfTax": {
     "auth_ref": [
      "r50",
      "r53",
      "r55",
      "r59",
      "r289",
      "r410",
      "r415",
      "r416",
      "r519",
      "r558"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_ComprehensiveIncomeNetOfTax",
       "weight": 1.0
      }
     },
     "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",
        "totalLabel": "Other comprehensive (loss) income",
        "verboseLabel": "Other comprehensive income (loss)"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax": {
     "auth_ref": [
      "r42",
      "r46",
      "r47",
      "r225"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossBeforeTax",
       "weight": -1.0
      },
      "http://www.firstib.com/role/SecuritiesSecuritiesAmountsReclassifiedfromAccumulatedOtherComprehensiveIncomeLossDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before tax of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.",
        "label": "Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax",
        "negatedTerseLabel": "Reclassification adjustment for gains (losses) realized",
        "verboseLabel": "Total reclassified amount before tax"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited",
      "http://www.firstib.com/role/SecuritiesSecuritiesAmountsReclassifiedfromAccumulatedOtherComprehensiveIncomeLossDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax": {
     "auth_ref": [
      "r42",
      "r46",
      "r47",
      "r225"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesSecuritiesAmountsReclassifiedfromAccumulatedOtherComprehensiveIncomeLossDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.",
        "label": "Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax",
        "totalLabel": "Total reclassifications out of accumulated other comprehensive loss"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesSecuritiesAmountsReclassifiedfromAccumulatedOtherComprehensiveIncomeLossDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax": {
     "auth_ref": [
      "r43",
      "r225"
     ],
     "calculation": {
      "http://www.firstib.com/role/SecuritiesSecuritiesAmountsReclassifiedfromAccumulatedOtherComprehensiveIncomeLossDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.",
        "label": "Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax",
        "terseLabel": "Tax expense (benefit)"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesSecuritiesAmountsReclassifiedfromAccumulatedOtherComprehensiveIncomeLossDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossTax": {
     "auth_ref": [
      "r43",
      "r59",
      "r343",
      "r352",
      "r354",
      "r410",
      "r413",
      "r416",
      "r519",
      "r558"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited": {
       "order": 1.0,
       "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",
        "terseLabel": "Income tax (benefit) provision"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1": {
     "auth_ref": [
      "r355",
      "r356",
      "r359"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of tax expense (benefit) allocated to other comprehensive income (loss) attributable to parent entity.",
        "label": "Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent",
        "terseLabel": "Income tax provision (benefit)"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossTaxPortionAttributableToParent1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax": {
     "auth_ref": [
      "r36",
      "r42",
      "r393"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).",
        "label": "Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax",
        "terseLabel": "Amount of Loss Recognized in Other Comprehensive Income"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsEffectOfDerivativesonIncomeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherNoninterestExpense": {
     "auth_ref": [
      "r531"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 8.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of noninterest expense classified as other.",
        "label": "Other Noninterest Expense",
        "verboseLabel": "Other"
       }
      }
     },
     "localname": "OtherNoninterestExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherRealEstate": {
     "auth_ref": [
      "r509"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 10.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.",
        "label": "Other Real Estate",
        "terseLabel": "Impaired loans",
        "verboseLabel": "Other real estate owned"
       }
      }
     },
     "localname": "OtherRealEstate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PassMember": {
     "auth_ref": [
      "r181",
      "r244"
     ],
     "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"
       }
      }
     },
     "localname": "PassMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PastDueFinancingReceivablesTableTextBlock": {
     "auth_ref": [
      "r187",
      "r188",
      "r240",
      "r251"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of aging analysis for financing receivable.",
        "label": "Financing Receivable, Past Due [Table Text Block]",
        "terseLabel": "Past Due Financing Receivables"
       }
      }
     },
     "localname": "PastDueFinancingReceivablesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_PaymentsForOriginationAndPurchasesOfLoansHeldForSale": {
     "auth_ref": [
      "r77"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 17.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The aggregate amount of cash outflow for loans purchased and created with the intention to resell them in the near future.",
        "label": "Payments for Origination and Purchases of Loans Held-for-sale",
        "negatedLabel": "Loans originated for sale",
        "terseLabel": "Loans originated for sale"
       }
      }
     },
     "localname": "PaymentsForOriginationAndPurchasesOfLoansHeldForSale",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited",
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsForProceedsFromLoansAndLeases": {
     "auth_ref": [
      "r99"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 7.0,
       "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": "Net loan activity, excluding purchases"
       }
      }
     },
     "localname": "PaymentsForProceedsFromLoansAndLeases",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsForRepurchaseOfCommonStock": {
     "auth_ref": [
      "r73"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 8.0,
       "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",
        "negatedTerseLabel": "Repurchase of common stock"
       }
      }
     },
     "localname": "PaymentsForRepurchaseOfCommonStock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsOfDividends": {
     "auth_ref": [
      "r73"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 7.0,
       "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": "Cash dividends paid"
       }
      }
     },
     "localname": "PaymentsOfDividends",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt": {
     "auth_ref": [
      "r66",
      "r68",
      "r197"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 5.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash outflow to acquire investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Payments to Acquire Debt Securities, Available-for-sale",
        "negatedLabel": "Purchase of securities available-for-sale"
       }
      }
     },
     "localname": "PaymentsToAcquireAvailableForSaleSecuritiesDebt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquireFederalHomeLoanBankStock": {
     "auth_ref": [
      "r69"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash outflow to acquire Federal Home Loan Bank (FHLB) stock.",
        "label": "Payments to Acquire Federal Home Loan Bank Stock",
        "negatedTerseLabel": "Purchase of Federal Home Loan Bank of Indianapolis stock"
       }
      }
     },
     "localname": "PaymentsToAcquireFederalHomeLoanBankStock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquireHeldToMaturitySecurities": {
     "auth_ref": [
      "r68",
      "r197"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 4.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash outflow through purchase of long-term held-to-maturity securities.",
        "label": "Payments to Acquire Held-to-maturity Securities",
        "negatedTerseLabel": "Purchase of securities held-to-maturity"
       }
      }
     },
     "localname": "PaymentsToAcquireHeldToMaturitySecurities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquireLand": {
     "auth_ref": [
      "r70"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash outflow from the acquisition of real estate intended to generate income for the owner; excludes land acquired for use by the owner.",
        "label": "Payments to Acquire Land",
        "terseLabel": "Payments to acquire land"
       }
      }
     },
     "localname": "PaymentsToAcquireLand",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquireLoansReceivable": {
     "auth_ref": [
      "r68"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 9.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash outflow for the purchase of loan receivable arising from the financing of goods and services.",
        "label": "Payments to Acquire Loans Receivable",
        "negatedLabel": "Loans purchased"
       }
      }
     },
     "localname": "PaymentsToAcquireLoansReceivable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquirePropertyPlantAndEquipment": {
     "auth_ref": [
      "r70"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.",
        "label": "Payments to Acquire Property, Plant, and Equipment",
        "negatedLabel": "Purchase of premises and equipment"
       }
      }
     },
     "localname": "PaymentsToAcquirePropertyPlantAndEquipment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PerformingFinancingReceivableMember": {
     "auth_ref": [
      "r181",
      "r244"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Category status of financial instruments in which payments are received or paid on a timely basis in accordance with the terms of the contract. Financial instruments include, but are not limited to, financing receivables, loans, debt instruments, and investments.",
        "label": "Performing Financial Instruments [Member]",
        "terseLabel": "Performing"
       }
      }
     },
     "localname": "PerformingFinancingReceivableMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PlanNameAxis": {
     "auth_ref": [
      "r321",
      "r332"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by plan name for share-based payment arrangement.",
        "label": "Plan Name [Axis]",
        "terseLabel": "Plan Name [Axis]"
       }
      }
     },
     "localname": "PlanNameAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PlanNameDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Plan name for share-based payment arrangement.",
        "label": "Plan Name [Domain]",
        "terseLabel": "Plan Name [Domain]"
       }
      }
     },
     "localname": "PlanNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PortionAtFairValueFairValueDisclosureMember": {
     "auth_ref": [
      "r404"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Measured at fair value for financial reporting purposes.",
        "label": "Portion at Fair Value Measurement [Member]",
        "terseLabel": "Portion at Fair Value Measurement [Member]"
       }
      }
     },
     "localname": "PortionAtFairValueFairValueDisclosureMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PreferredStockParOrStatedValuePerShare": {
     "auth_ref": [
      "r10"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_PreferredStockSharesAuthorized": {
     "auth_ref": [
      "r10"
     ],
     "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",
        "verboseLabel": "Preferred stock, shares authorized (in shares)"
       }
      }
     },
     "localname": "PreferredStockSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockSharesIssued": {
     "auth_ref": [
      "r10"
     ],
     "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",
        "verboseLabel": "Preferred stock, shares issued (in shares)"
       }
      }
     },
     "localname": "PreferredStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockSharesOutstanding": {
     "auth_ref": [
      "r10"
     ],
     "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",
        "verboseLabel": "Preferred stock, share outstanding (in shares)"
       }
      }
     },
     "localname": "PreferredStockSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockValue": {
     "auth_ref": [
      "r10"
     ],
     "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, Issued",
        "verboseLabel": "Preferred stock, no par value; 4,913,779 shares authorized; issued and outstanding - none"
       }
      }
     },
     "localname": "PreferredStockValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PrincipleTransactionRevenueLineItems": {
     "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": "Principal Transaction Revenue [Line Items]",
        "terseLabel": "Principal Transaction Revenue [Line Items]"
       }
      }
     },
     "localname": "PrincipleTransactionRevenueLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PrincipleTransactionRevenueTable": {
     "auth_ref": [
      "r498"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule of revenue by reporting categories or types of financial instruments, including derivatives but excluding dividends and interests, from trading for own account by broker dealers. This element may be used for the entire principal transactions revenue schedule.",
        "label": "Principal Transaction Revenue [Table]",
        "terseLabel": "Principal Transaction Revenue [Table]"
       }
      }
     },
     "localname": "PrincipleTransactionRevenueTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ProceedsFromFederalHomeLoanBankBorrowings": {
     "auth_ref": [
      "r71"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 6.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash inflow from Federal Home Loan Bank (FHLBank) borrowing, classified as financing activity.",
        "label": "Proceeds from FHLBank Borrowings, Financing Activities",
        "terseLabel": "Proceeds from advances from Federal Home Loan Bank"
       }
      }
     },
     "localname": "ProceedsFromFederalHomeLoanBankBorrowings",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt": {
     "auth_ref": [
      "r71"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash inflow from a borrowing where a lender is placed in a lien position behind debt having a higher priority of repayment (senior) in liquidation of the entity's assets or underlying collateral.",
        "label": "Proceeds from Issuance of Subordinated Long-term Debt",
        "terseLabel": "Net proceeds from issuance of subordinated debt"
       }
      }
     },
     "localname": "ProceedsFromIssuanceOfSubordinatedLongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities": {
     "auth_ref": [
      "r66",
      "r67",
      "r197"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 8.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash inflow from maturity, prepayment and call of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale",
        "verboseLabel": "Maturities and calls of securities available-for-sale"
       }
      }
     },
     "localname": "ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromPaymentsForOtherFinancingActivities": {
     "auth_ref": [
      "r72",
      "r75",
      "r99"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 3.0,
       "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, net"
       }
      }
     },
     "localname": "ProceedsFromPaymentsForOtherFinancingActivities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromRepaymentsOfShortTermDebt": {
     "auth_ref": [
      "r99"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 4.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The net cash inflow or outflow for borrowing having initial term of repayment within one year or the normal operating cycle, if longer.",
        "label": "Proceeds from (Repayments of) Short-term Debt",
        "terseLabel": "Short-term borrowings"
       }
      }
     },
     "localname": "ProceedsFromRepaymentsOfShortTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt": {
     "auth_ref": [
      "r66",
      "r67",
      "r197"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 6.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash inflow from sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Proceeds from Sale of Debt Securities, Available-for-sale",
        "terseLabel": "Proceeds from sale of securities available-for-sale"
       }
      }
     },
     "localname": "ProceedsFromSaleOfAvailableForSaleSecuritiesDebt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleOfLoansHeldForInvestment": {
     "auth_ref": [
      "r67"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash inflow from Sales of Loans Held For Investment.",
        "label": "Proceeds from Sale of Loans Held-for-investment",
        "terseLabel": "Net proceeds from sale of portfolio loans"
       }
      }
     },
     "localname": "ProceedsFromSaleOfLoansHeldForInvestment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleOfMortgageLoansHeldForSale": {
     "auth_ref": [
      "r77",
      "r79"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 15.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash inflow from sales of loans that are secured with real estate mortgages and are held with the intention to resell in the near future.",
        "label": "Proceeds from Sale of Mortgage Loans Held-for-sale",
        "terseLabel": "Proceeds from sale of loans"
       }
      }
     },
     "localname": "ProceedsFromSaleOfMortgageLoansHeldForSale",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited",
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProfessionalFees": {
     "auth_ref": [
      "r581",
      "r582"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_NoninterestExpense",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A fee charged for services from professionals such as doctors, lawyers and accountants. The term is often expanded to include other professions, for example, pharmacists charging to maintain a medicinal profile of a client or customer.",
        "label": "Professional Fees",
        "verboseLabel": "Consulting and professional services"
       }
      }
     },
     "localname": "ProfessionalFees",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Property, Plant and Equipment [Abstract]",
        "terseLabel": "Property, Plant and Equipment [Abstract]"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentByTypeAxis": {
     "auth_ref": [
      "r19",
      "r265"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of long-lived, physical assets used to produce goods and services and not intended for resale.",
        "label": "Long-Lived Tangible Asset [Axis]",
        "terseLabel": "Property, Plant and Equipment, Type [Axis]"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentByTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock": {
     "auth_ref": [
      "r267",
      "r587",
      "r588",
      "r589"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for long-lived, physical asset used in normal conduct of business and not intended for resale. Includes, but is not limited to, work of art, historical treasure, and similar asset classified as collections.",
        "label": "Property, Plant and Equipment Disclosure [Text Block]",
        "terseLabel": "Premises and Equipment"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipment"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentGross": {
     "auth_ref": [
      "r18",
      "r263"
     ],
     "calculation": {
      "http://www.firstib.com/role/SummaryDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_PropertyPlantAndEquipmentNet",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.",
        "label": "Property, Plant and Equipment, Gross",
        "terseLabel": "Premises and equipment, gross"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentGross",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentLineItems": {
     "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": "Property, Plant and Equipment [Line Items]",
        "terseLabel": "Property, Plant and Equipment [Line Items]"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails",
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentNet": {
     "auth_ref": [
      "r3",
      "r4",
      "r265",
      "r554"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 8.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      },
      "http://www.firstib.com/role/SummaryDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.",
        "label": "Property, Plant and Equipment, Net",
        "totalLabel": "Premises and equipment, net",
        "verboseLabel": "Premises and equipment, net"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentTextBlock": {
     "auth_ref": [
      "r3",
      "r265"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, balances by class of assets, depreciation and depletion expense and method used, including composite depreciation, and accumulated deprecation.",
        "label": "Property, Plant and Equipment [Table Text Block]",
        "terseLabel": "Property, Plant and Equipment"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentTypeDomain": {
     "auth_ref": [
      "r3",
      "r263"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Listing of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.",
        "label": "Long-Lived Tangible Asset [Domain]",
        "terseLabel": "Property, Plant and Equipment, Type [Domain]"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ProvisionForLoanAndLeaseLosses": {
     "auth_ref": [
      "r82",
      "r168",
      "r525"
     ],
     "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 (credit) charged to expense"
       }
      }
     },
     "localname": "ProvisionForLoanAndLeaseLosses",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProvisionForLoanLossesExpensed": {
     "auth_ref": [
      "r238",
      "r516"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 18.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      },
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 2.0,
       "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": "Financing Receivable, Credit Loss, Expense (Reversal)",
        "terseLabel": "Provision for loan losses",
        "verboseLabel": "Provision for Loan Losses"
       }
      }
     },
     "localname": "ProvisionForLoanLossesExpensed",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RealEstateMember": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Property consisting of land, land improvement and buildings.",
        "label": "Real Estate [Member]",
        "terseLabel": "Investor commercial real estate"
       }
      }
     },
     "localname": "RealEstateMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ReceivablesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Receivables [Abstract]",
        "terseLabel": "Receivables [Abstract]"
       }
      }
     },
     "localname": "ReceivablesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent": {
     "auth_ref": [
      "r45"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount before tax of reclassification adjustments of other comprehensive income (loss) attributable to parent.",
        "label": "Reclassification from AOCI, Current Period, before Tax, Attributable to Parent",
        "terseLabel": "Reclassification of net loss realized and included in earnings"
       }
      }
     },
     "localname": "ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RepaymentsOfFederalHomeLoanBankBorrowings": {
     "auth_ref": [
      "r74"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 5.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash outflow for repayment of Federal Home Loan Bank (FHLBank) borrowing, classified as financing activity.",
        "label": "Payments of FHLBank Borrowings, Financing Activities",
        "negatedLabel": "Repayment of advances from Federal Home Loan Bank"
       }
      }
     },
     "localname": "RepaymentsOfFederalHomeLoanBankBorrowings",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ResidentialMortgageMember": {
     "auth_ref": [
      "r250"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Loan to purchase or refinance residential real estate for example, but not limited to, a home, in which the real estate itself serves as collateral for the loan.",
        "label": "Residential Mortgage [Member]",
        "terseLabel": "Residential mortgage"
       }
      }
     },
     "localname": "ResidentialMortgageMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RestrictedStockMember": {
     "auth_ref": [
      "r135"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Stock including a provision that prohibits sale or substantive sale of an equity instrument for a specified period of time or until specified performance conditions are met.",
        "label": "Restricted Stock [Member]",
        "terseLabel": "Restricted Stock Awards"
       }
      }
     },
     "localname": "RestrictedStockMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails",
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RestrictedStockUnitsRSUMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Share instrument which is convertible to stock or an equivalent amount of cash, after a specified period of time or when specified performance conditions are met.",
        "label": "Restricted Stock Units (RSUs) [Member]",
        "terseLabel": "Restricted Stock Units"
       }
      }
     },
     "localname": "RestrictedStockUnitsRSUMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RetainedEarningsAccumulatedDeficit": {
     "auth_ref": [
      "r12",
      "r296",
      "r341",
      "r552",
      "r574",
      "r579"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cumulative amount of the reporting entity's undistributed earnings or deficit.",
        "label": "Retained Earnings (Accumulated Deficit)",
        "verboseLabel": "Retained earnings"
       }
      }
     },
     "localname": "RetainedEarningsAccumulatedDeficit",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RetainedEarningsMember": {
     "auth_ref": [
      "r100",
      "r101",
      "r102",
      "r107",
      "r117",
      "r119",
      "r232",
      "r337",
      "r338",
      "r339",
      "r346",
      "r347",
      "r570",
      "r572"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax": {
     "auth_ref": [
      "r146",
      "r147",
      "r152",
      "r157",
      "r158",
      "r162",
      "r163",
      "r164",
      "r297",
      "r298",
      "r491"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_NoninterestIncome",
       "weight": 1.0
      },
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.",
        "label": "Revenue from Contract with Customer, Including Assessed Tax",
        "terseLabel": "Loan servicing revenue",
        "totalLabel": "Net revenue from mortgage banking activities",
        "verboseLabel": "Noninterest income"
       }
      }
     },
     "localname": "RevenueFromContractWithCustomerIncludingAssessedTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/MortgageBankingActivitiesDetails",
      "http://www.firstib.com/role/ServicingAssetNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability": {
     "auth_ref": [
      "r428",
      "r433"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase in right-of-use asset obtained in exchange for finance lease liability.",
        "label": "Right-of-Use Asset Obtained in Exchange for Finance Lease Liability",
        "terseLabel": "Initial recognition of right-of-use asset"
       }
      }
     },
     "localname": "RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable": {
     "auth_ref": [
      "r26"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails",
      "http://www.firstib.com/role/LoansChangeintheBalancesoftheALLLDetails",
      "http://www.firstib.com/role/LoansImpairedLoansDetails",
      "http://www.firstib.com/role/LoansLoanPortfolioAgingDetails",
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails",
      "http://www.firstib.com/role/LoansRecordedInvestmentsinLoansDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock": {
     "auth_ref": [
      "r26"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the various 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 Text Block]",
        "terseLabel": "Schedule of Accounts, Notes, Loans and Financing Receivable"
       }
      }
     },
     "localname": "ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock": {
     "auth_ref": [
      "r45",
      "r415",
      "r416"
     ],
     "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)",
        "verboseLabel": "Schedule of Accumulated Other Comprehensive Income (Loss)"
       }
      }
     },
     "localname": "ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossTables",
      "http://www.firstib.com/role/SecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the reconciliation of available-for-sale securities from cost basis to fair value.",
        "label": "Schedule of Available-for-sale Securities Reconciliation [Table Text Block]",
        "terseLabel": "Schedule of Available-for-sale Securities Reconciliation"
       }
      }
     },
     "localname": "ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SecuritiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfCashFlowHedgesIncludedInAccumulatedOtherComprehensiveIncomeLossTableTextBlock": {
     "auth_ref": [
      "r376"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of gain (loss) on derivative and nonderivative instruments designated and qualifying as cash flow hedge recorded in accumulated other comprehensive income (AOCI) and reclassified into earnings.",
        "label": "Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block]",
        "terseLabel": "Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss)"
       }
      }
     },
     "localname": "ScheduleOfCashFlowHedgesIncludedInAccumulatedOtherComprehensiveIncomeLossTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock": {
     "auth_ref": [
      "r369",
      "r379",
      "r385"
     ],
     "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": "Derivative Instruments, Gain (Loss) [Table Text Block]",
        "terseLabel": "Schedule Of Effects Of Interest Rate Swap Agreements On Statements Of Income"
       }
      }
     },
     "localname": "ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock": {
     "auth_ref": [
      "r374"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the location and fair value amounts of derivative instruments (and nonderivative instruments that are designated and qualify as hedging instruments) reported in the statement of financial position.",
        "label": "Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]",
        "terseLabel": "Schedule of Derivative Instruments in Statement of Financial Position, Fair Value"
       }
      }
     },
     "localname": "ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable": {
     "auth_ref": [
      "r244",
      "r250"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about credit quality indicator for financing receivable.",
        "label": "Financing Receivable, Credit Quality Indicator [Table]",
        "terseLabel": "Financing Receivable, Credit Quality Indicator [Table]"
       }
      }
     },
     "localname": "ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansLoansInternalCreditAssessmentDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfParticipatingMortgageLoansTextBlock": {
     "auth_ref": [
      "r284"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the terms and amounts of participation in loan arrangements.",
        "label": "Schedule of Participating Mortgage Loans [Table Text Block]",
        "terseLabel": "Schedule of Participating Mortgage Loans"
       }
      }
     },
     "localname": "ScheduleOfParticipatingMortgageLoansTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/MortgageBankingActivitiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfPropertyPlantAndEquipmentTable": {
     "auth_ref": [
      "r19",
      "r265"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of information about physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, balances by class of assets, depreciation and depletion expense and method used, including composite depreciation, and accumulated deprecation.",
        "label": "Property, Plant and Equipment [Table]",
        "terseLabel": "Property, Plant and Equipment [Table]"
       }
      }
     },
     "localname": "ScheduleOfPropertyPlantAndEquipmentTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/PremisesandEquipmentNarrativeDetails",
      "http://www.firstib.com/role/SummaryDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfServicingAssetsAtFairValueTextBlock": {
     "auth_ref": [
      "r470"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the activity in the balance of servicing assets (including a description of where changes in fair value are reported in the statement of income for each period for which results of operations are presented), including but not limited to, the following: beginning and ending balances, additions (for instance, through purchases of servicing assets), disposals, changes in fair value during the period resulting from changes in inputs or assumptions used in the valuation model, other changes in fair value along with a description of those changes, and other changes that affect the balance along with a description of those changes.",
        "label": "Schedule of Servicing Assets at Fair Value [Table Text Block]",
        "terseLabel": "Schedule of Servicing Assets at Fair Value"
       }
      }
     },
     "localname": "ScheduleOfServicingAssetsAtFairValueTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/ServicingAssetTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfStockByClassTable": {
     "auth_ref": [
      "r24",
      "r92",
      "r143",
      "r144",
      "r286",
      "r287",
      "r288",
      "r290",
      "r291",
      "r292",
      "r293",
      "r294",
      "r295",
      "r296"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Schedule detailing information related to equity by class of stock. Class of stock includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. It also includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity.",
        "label": "Schedule of Stock by Class [Table]",
        "terseLabel": "Schedule of Stock by Class [Table]"
       }
      }
     },
     "localname": "ScheduleOfStockByClassTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/Cover"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfSubordinatedBorrowingTextBlock": {
     "auth_ref": [
      "r545"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of borrowings under subordinated debt agreements that qualify as available in computing net capital under SEC uniform net capital rules for broker-dealers, including restrictive covenants, collateral, interest rates and due dates, amounts due by date and amount owed in total.",
        "label": "Schedule of Subordinated Borrowing [Table Text Block]",
        "terseLabel": "Schedule of Subordinated Borrowing"
       }
      }
     },
     "localname": "ScheduleOfSubordinatedBorrowingTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock": {
     "auth_ref": [
      "r136"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the weighted average number of shares used in calculating basic net earnings per share (or unit) and diluted earnings per share (or unit).",
        "label": "Schedule of Weighted Average Number of Shares [Table Text Block]",
        "terseLabel": "Schedule of Weighted Average Number of Shares"
       }
      }
     },
     "localname": "ScheduleOfWeightedAverageNumberOfSharesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/EarningsPerShareTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ServicingAsset": {
     "auth_ref": [
      "r466"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 13.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate amount of servicing assets that are subsequently measured at fair value and servicing assets that are subsequently measured using the amortization method.",
        "label": "Servicing Asset",
        "terseLabel": "Servicing asset, at fair value",
        "verboseLabel": "Servicing asset"
       }
      }
     },
     "localname": "ServicingAsset",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ServicingAssetAtFairValueAdditions": {
     "auth_ref": [
      "r472"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The value of new servicing assets, subsequently measured at fair value, acquired or created during the current period through purchases or from transfers of financial assets.",
        "label": "Servicing Asset at Fair Value, Additions",
        "terseLabel": "Additions"
       }
      }
     },
     "localname": "ServicingAssetAtFairValueAdditions",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/ServicingAssetDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ServicingAssetAtFairValueAmount": {
     "auth_ref": [
      "r464",
      "r465",
      "r466",
      "r471"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.",
        "label": "Servicing Asset at Fair Value, Amount",
        "periodEndLabel": "Ending balance",
        "periodStartLabel": "Beginning balance"
       }
      }
     },
     "localname": "ServicingAssetAtFairValueAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/ServicingAssetDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ServicingAssetAtFairValueAmountRollForward": {
     "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": "Servicing Asset at Fair Value, Amount [Roll Forward]",
        "terseLabel": "Servicing Asset at Fair Value, Amount [Roll Forward]"
       }
      }
     },
     "localname": "ServicingAssetAtFairValueAmountRollForward",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/ServicingAssetDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ServicingAssetAtFairValueChangesInFairValueResultingFromChangesInValuationInputsOrChangesInAssumptions": {
     "auth_ref": [
      "r474"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase (decrease) in fair value from changes in the inputs, assumptions, or model used to calculate the fair value of the contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.",
        "label": "Servicing Asset at Fair Value, Changes in Fair Value Resulting from Changes in Valuation Inputs or Changes in Assumptions",
        "terseLabel": "Changes in fair value"
       }
      }
     },
     "localname": "ServicingAssetAtFairValueChangesInFairValueResultingFromChangesInValuationInputsOrChangesInAssumptions",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/ServicingAssetDetails",
      "http://www.firstib.com/role/ServicingAssetNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueDiscountRate": {
     "auth_ref": [
      "r469"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Discount rate used to estimate the fair value of servicing assets and servicing liabilities.",
        "label": "Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate",
        "terseLabel": "Servicing asset, discount rate"
       }
      }
     },
     "localname": "ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueDiscountRate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_ServicingAssetsAtFairValueLineItems": {
     "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": "Servicing Assets at Fair Value [Line Items]",
        "terseLabel": "Servicing Assets at Fair Value [Line Items]"
       }
      }
     },
     "localname": "ServicingAssetsAtFairValueLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/ServicingAssetNarrativeDetails",
      "http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ServicingAssetsAtFairValueTable": {
     "auth_ref": [
      "r471",
      "r472",
      "r473",
      "r474",
      "r484"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Activity in the balance of servicing assets subsequently measured at fair value (including a description of where changes in fair value are reported in the statement of income for each period for which results of operations are presented), including but not limited to, the following: beginning and ending balances, additions (through purchases of servicing assets and servicing assets that result from transfers of financial assets), disposals, changes in fair value during the period resulting from changes in valuations inputs or assumptions used in the valuation model, other changes in fair value along with a description of those changes, and other changes that affect the balance along with a description of those changes.",
        "label": "Schedule of Servicing Assets at Fair Value [Table]",
        "terseLabel": "Schedule of Servicing Assets at Fair Value [Table]"
       }
      }
     },
     "localname": "ServicingAssetsAtFairValueTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/ServicingAssetNarrativeDetails",
      "http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ShareBasedCompensation": {
     "auth_ref": [
      "r82"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited": {
       "order": 12.0,
       "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 Payment Arrangement, Noncash Expense",
        "verboseLabel": "Share-based compensation expense"
       }
      }
     },
     "localname": "ShareBasedCompensation",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod": {
     "auth_ref": [
      "r325"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period",
        "negatedLabel": "Vested"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue": {
     "auth_ref": [
      "r329"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value",
        "terseLabel": "Vested"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod": {
     "auth_ref": [
      "r327"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period",
        "terseLabel": "Granted"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue": {
     "auth_ref": [
      "r327"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value",
        "terseLabel": "Granted"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber": {
     "auth_ref": [
      "r326"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number",
        "periodEndLabel": "Balance at end of period",
        "periodStartLabel": "Balance at beginning of period"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward": {
     "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": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]",
        "terseLabel": "Awards/Units Outstanding (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue": {
     "auth_ref": [
      "r326"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value",
        "periodEndLabel": "Balance at end of period",
        "periodStartLabel": "Balance at beginning of period"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward": {
     "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": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]",
        "terseLabel": "Weighted-Average Grant Date Fair Value Per Share (in dollars per share)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod": {
     "auth_ref": [
      "r328"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period",
        "negatedLabel": "Vested"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue": {
     "auth_ref": [
      "r328"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value",
        "terseLabel": "Vested"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward": {
     "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": "Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]",
        "terseLabel": "Deferred Stock Rights"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDeferredStockRightsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized": {
     "auth_ref": [
      "r322"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of shares authorized for issuance under share-based payment arrangement.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized",
        "terseLabel": "Number of shares authorized (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain": {
     "auth_ref": [
      "r319",
      "r323"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Award under share-based payment arrangement.",
        "label": "Award Type [Domain]",
        "terseLabel": "Award Type [Domain]"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails",
      "http://www.firstib.com/role/BenefitPlansDetailsTextual"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SpecialMentionMember": {
     "auth_ref": [
      "r181",
      "r244"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_StatementClassOfStockAxis": {
     "auth_ref": [
      "r9",
      "r10",
      "r11",
      "r92",
      "r93",
      "r125",
      "r129",
      "r130",
      "r132",
      "r134",
      "r143",
      "r144",
      "r145",
      "r228",
      "r289",
      "r408"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by the different classes of stock of the entity.",
        "label": "Class of Stock [Axis]",
        "terseLabel": "Class of Stock [Axis]"
       }
      }
     },
     "localname": "StatementClassOfStockAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited",
      "http://www.firstib.com/role/Cover"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementEquityComponentsAxis": {
     "auth_ref": [
      "r25",
      "r100",
      "r101",
      "r102",
      "r107",
      "r117",
      "r119",
      "r142",
      "r232",
      "r289",
      "r296",
      "r337",
      "r338",
      "r339",
      "r346",
      "r347",
      "r410",
      "r411",
      "r412",
      "r413",
      "r414",
      "r416",
      "r570",
      "r571",
      "r572"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by component of equity.",
        "label": "Equity Components [Axis]",
        "terseLabel": "Equity Components [Axis]"
       }
      }
     },
     "localname": "StatementEquityComponentsAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails",
      "http://www.firstib.com/role/BenefitPlansDetailsTextual",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails",
      "http://www.firstib.com/role/BenefitPlansDetailsTextual",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails",
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfCashFlowsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statement of Cash Flows [Abstract]",
        "terseLabel": "Statement of Cash Flows [Abstract]"
       }
      }
     },
     "localname": "StatementOfCashFlowsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfFinancialPositionAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statement of Financial Position [Abstract]",
        "terseLabel": "Statement of Financial Position [Abstract]"
       }
      }
     },
     "localname": "StatementOfFinancialPositionAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statement of Comprehensive Income [Abstract]",
        "terseLabel": "Statement of Comprehensive Income [Abstract]"
       }
      }
     },
     "localname": "StatementOfIncomeAndComprehensiveIncomeAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfStockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statement of Stockholders' Equity [Abstract]",
        "terseLabel": "Statement of Stockholders' Equity [Abstract]"
       }
      }
     },
     "localname": "StatementOfStockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementTable": {
     "auth_ref": [
      "r100",
      "r101",
      "r102",
      "r142",
      "r491"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansActivityDetails",
      "http://www.firstib.com/role/BenefitPlansDetailsTextual",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheetsParenthetical",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsCarryingValueandEstimatedFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails",
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation": {
     "auth_ref": [
      "r10",
      "r11",
      "r296",
      "r320",
      "r330"
     ],
     "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": "Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture",
        "terseLabel": "Allocated share-based compensation expense",
        "verboseLabel": "Recognition of the fair value of share-based compensation"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueShareBasedCompensation",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/BenefitPlansDetailsTextual",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueStockDividend": {
     "auth_ref": [
      "r25",
      "r289",
      "r296"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value of stock issued to shareholders as a dividend during the period.",
        "label": "Stock Issued During Period, Value, Stock Dividend",
        "terseLabel": "Deferred stock rights and restricted stock units issued in lieu of cash dividends payable on outstanding deferred stock rights and restricted stock units"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueStockDividend",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockRepurchasedDuringPeriodValue": {
     "auth_ref": [
      "r10",
      "r11",
      "r289",
      "r296"
     ],
     "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",
        "negatedTerseLabel": "Repurchase of common stock"
       }
      }
     },
     "localname": "StockRepurchasedDuringPeriodValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquity": {
     "auth_ref": [
      "r11",
      "r14",
      "r15",
      "r93",
      "r189",
      "r228",
      "r408"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "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 Attributable to Parent",
        "periodEndLabel": "Balance, end of period",
        "periodStartLabel": "Balance, beginning of period",
        "terseLabel": "Total shareholders\u2019 equity"
       }
      }
     },
     "localname": "StockholdersEquity",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/AccumulatedOtherComprehensiveLossDetails",
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets",
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Stockholders' Equity Attributable to Parent [Abstract]",
        "verboseLabel": "Shareholders\u2019 Equity"
       }
      }
     },
     "localname": "StockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockholdersEquityNoteAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Stockholders' Equity Note [Abstract]",
        "terseLabel": "Stockholders' Equity Note [Abstract]"
       }
      }
     },
     "localname": "StockholdersEquityNoteAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_SubordinatedDebt": {
     "auth_ref": [
      "r6",
      "r8",
      "r506",
      "r550"
     ],
     "calculation": {
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 3.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.",
        "label": "Subordinated Debt",
        "verboseLabel": "Subordinated debt, net of unamortized debt issuance costs of $2,319 and $2,472 in 2020 and 2019, respectively"
       }
      }
     },
     "localname": "SubordinatedDebt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual",
      "http://www.firstib.com/role/SubordinatedDebtScheduleofSubordinatedDebtDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SubstandardMember": {
     "auth_ref": [
      "r181",
      "r244"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A category of financing receivables that are inadequately protected by the current sound worth and paying capacity of the obligor or of the collateral pledged, if any. Loans so classified have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that the creditor will sustain some loss if the deficiencies are not corrected.",
        "label": "Substandard [Member]",
        "terseLabel": "Substandard"
       }
      }
     },
     "localname": "SubstandardMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansNonaccrualLoansDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SupplementalCashFlowInformationAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Supplemental Cash Flow Information [Abstract]",
        "verboseLabel": "Supplemental Disclosures"
       }
      }
     },
     "localname": "SupplementalCashFlowInformationAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_TransferOfPortfolioLoansAndLeasesToHeldForSale1": {
     "auth_ref": [
      "r88",
      "r89",
      "r90"
     ],
     "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-sale",
        "terseLabel": "Loans transferred to held-for-sale from portfolio"
       }
      }
     },
     "localname": "TransferOfPortfolioLoansAndLeasesToHeldForSale1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TransferToOtherRealEstate": {
     "auth_ref": [
      "r88",
      "r89",
      "r90"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Value transferred from mortgage loans to real estate owned (REO) in noncash transactions.",
        "label": "Real Estate Owned, Transfer to Real Estate Owned",
        "terseLabel": "Loans transferred to other real estate owned"
       }
      }
     },
     "localname": "TransferToOtherRealEstate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TransfersAndServicingAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Transfers and Servicing [Abstract]",
        "terseLabel": "Transfers and Servicing [Abstract]"
       }
      }
     },
     "localname": "TransfersAndServicingAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_TransfersAndServicingOfFinancialAssetsTextBlock": {
     "auth_ref": [
      "r439",
      "r440",
      "r445",
      "r449",
      "r450",
      "r451",
      "r456",
      "r458",
      "r460",
      "r461",
      "r463",
      "r467",
      "r468",
      "r469",
      "r470",
      "r475",
      "r476",
      "r483",
      "r485",
      "r489"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for a transferor's continuing involvement in financial assets that it has transferred in a securitization or asset-backed financing arrangement, the nature of any restrictions on assets reported by an entity in its statement of financial position that relate to a transferred financial asset (including the carrying amounts of such assets), how servicing assets and servicing liabilities are reported, and (for securitization or asset-backed financing arrangements accounted for as sales) when a transferor has continuing involvement with the transferred financial assets and transfers of financial assets accounted for as secured borrowings, how the transfer of financial assets affects an entity's financial position, financial performance, and cash flows.",
        "label": "Transfers and Servicing of Financial Assets [Text Block]",
        "terseLabel": "Servicing Asset"
       }
      }
     },
     "localname": "TransfersAndServicingOfFinancialAssetsTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/ServicingAsset"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain": {
     "auth_ref": [
      "r212",
      "r216",
      "r439",
      "r440",
      "r441",
      "r442",
      "r443",
      "r444",
      "r446",
      "r447",
      "r448",
      "r452",
      "r453",
      "r454",
      "r455",
      "r459",
      "r462",
      "r471",
      "r472",
      "r473",
      "r474",
      "r477",
      "r478",
      "r479",
      "r480",
      "r481",
      "r482",
      "r483",
      "r484",
      "r486",
      "r487",
      "r488"
     ],
     "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": "Financial Instruments [Domain]",
        "terseLabel": "Financial Instruments [Domain]"
       }
      }
     },
     "localname": "TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsGainLossRecognizedDetails",
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsNotionalAmountsandFairValueDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueRollForwardDetails",
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails",
      "http://www.firstib.com/role/SecuritiesCarryingValueDetails",
      "http://www.firstib.com/role/SecuritiesDetails",
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails",
      "http://www.firstib.com/role/ServicingAssetUnpaidprincipalbalanceDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_TypeOfAdoptionMember": {
     "auth_ref": [
      "r106",
      "r107",
      "r108",
      "r110",
      "r229",
      "r230",
      "r231",
      "r232",
      "r235",
      "r236",
      "r333",
      "r334",
      "r335",
      "r336",
      "r337",
      "r338",
      "r339",
      "r341",
      "r344",
      "r345",
      "r346",
      "r347",
      "r492",
      "r493",
      "r494",
      "r568",
      "r569",
      "r570",
      "r571",
      "r572",
      "r573",
      "r574",
      "r575",
      "r576",
      "r577",
      "r578",
      "r579"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amendment to accounting standards.",
        "label": "Accounting Standards Update [Domain]",
        "terseLabel": "Type of Adoption [Domain]"
       }
      }
     },
     "localname": "TypeOfAdoptionMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember": {
     "auth_ref": [
      "r307",
      "r538"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debentures, bonds and other debt securities issued by US government sponsored entities (GSEs), for example, but 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). Excludes debt issued by the Government National Mortgage Association (GNMA or Ginnie Mae).",
        "label": "US Government-sponsored Enterprises Debt Securities [Member]",
        "terseLabel": "U.S. Government-sponsored agencies"
       }
      }
     },
     "localname": "USGovernmentSponsoredEnterprisesDebtSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails",
      "http://www.firstib.com/role/SecuritiesDetails",
      "http://www.firstib.com/role/SecuritiesGrossUnrealizedLossesandFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_UnamortizedLoanCommitmentAndOriginationFeesAndUnamortizedDiscountsOrPremiums": {
     "auth_ref": [
      "r192"
     ],
     "calculation": {
      "http://www.firstib.com/role/LoansCategoriesDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.",
        "label": "Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums",
        "terseLabel": "Net deferred loan origination costs and premiums and discounts on purchased loans and other"
       }
      }
     },
     "localname": "UnamortizedLoanCommitmentAndOriginationFeesAndUnamortizedDiscountsOrPremiums",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/LoansCategoriesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ValuationTechniqueAxis": {
     "auth_ref": [
      "r397"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by valuation approach and technique.",
        "label": "Valuation Approach and Technique [Axis]",
        "terseLabel": "Valuation Approach and Technique [Axis]"
       }
      }
     },
     "localname": "ValuationTechniqueAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ValuationTechniqueDiscountedCashFlowMember": {
     "auth_ref": [
      "r397"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ValuationTechniqueDomain": {
     "auth_ref": [
      "r397"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Valuation approach and technique.",
        "label": "Valuation Approach and Technique [Domain]",
        "terseLabel": "Valuation Approach and Technique [Domain]"
       }
      }
     },
     "localname": "ValuationTechniqueDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/FairValueofFinancialInstrumentsQuantativeInformationAboutUnobservableInputsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_VariableRateAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of variable rate.",
        "label": "Variable Rate [Axis]",
        "terseLabel": "Variable Rate [Axis]"
       }
      }
     },
     "localname": "VariableRateAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "VariableRateDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/DerivativeFinancialInstrumentsInterestSwapDerivativesDetails",
      "http://www.firstib.com/role/SubordinatedDebtDetailsTextual"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment": {
     "auth_ref": [
      "r134"
     ],
     "calculation": {
      "http://www.firstib.com/role/EarningsPerShareDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.",
        "label": "Weighted Average Number Diluted Shares Outstanding Adjustment",
        "totalLabel": "Weighted-average common and incremental shares (in shares)"
       }
      }
     },
     "localname": "WeightedAverageNumberDilutedSharesOutstandingAdjustment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/EarningsPerShareDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]",
        "verboseLabel": "Diluted earnings per share"
       }
      }
     },
     "localname": "WeightedAverageNumberDilutedSharesOutstandingAdjustmentAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/EarningsPerShareDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding": {
     "auth_ref": [
      "r124",
      "r134"
     ],
     "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 Shares Outstanding, Diluted",
        "verboseLabel": "Diluted (in shares)"
       }
      }
     },
     "localname": "WeightedAverageNumberOfDilutedSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Weighted Average Number of Shares Outstanding, Diluted [Abstract]",
        "verboseLabel": "Weighted-Average Number of Common Shares Outstanding"
       }
      }
     },
     "localname": "WeightedAverageNumberOfSharesOutstandingAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_WeightedAverageNumberOfSharesOutstandingBasic": {
     "auth_ref": [
      "r123",
      "r134"
     ],
     "calculation": {
      "http://www.firstib.com/role/EarningsPerShareDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment",
       "weight": 1.0
      }
     },
     "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 (in shares)",
        "verboseLabel": "Weighted-average common shares (in shares)"
       }
      }
     },
     "localname": "WeightedAverageNumberOfSharesOutstandingBasic",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/CondensedConsolidatedStatementsofIncomeUnaudited",
      "http://www.firstib.com/role/EarningsPerShareDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_WeightedAverageNumberOfSharesOutstandingBasicAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Weighted Average Number of Shares Outstanding, Basic [Abstract]",
        "verboseLabel": "Basic earnings per share"
       }
      }
     },
     "localname": "WeightedAverageNumberOfSharesOutstandingBasicAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.firstib.com/role/EarningsPerShareDetails"
     ],
     "xbrltype": "stringItemType"
    }
   },
   "unitCount": 10
  }
 },
 "std_ref": {
  "r0": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760"
  },
  "r1": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "205",
   "URI": "http://asc.fasb.org/topic&trid=2122149"
  },
  "r10": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r100": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "23",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=115929471&loc=d3e21914-107793"
  },
  "r101": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "24",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=115929471&loc=d3e21930-107793"
  },
  "r102": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=115929471&loc=d3e21711-107793"
  },
  "r103": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=115929471&loc=d3e21728-107793"
  },
  "r104": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r105": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(1)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r106": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(2)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r107": {
   "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"
  },
  "r108": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(4)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r109": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r11": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r110": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r111": {
   "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"
  },
  "r112": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794"
  },
  "r113": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794"
  },
  "r114": {
   "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"
  },
  "r115": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794"
  },
  "r116": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22644-107794"
  },
  "r117": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22644-107794"
  },
  "r118": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794"
  },
  "r119": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794"
  },
  "r12": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r120": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 11.M.Q2)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=112272810&loc=d3e31137-122693"
  },
  "r121": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=112272810&loc=SL108384541-122693"
  },
  "r122": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "250",
   "URI": "http://asc.fasb.org/topic&trid=2122394"
  },
  "r123": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1448-109256"
  },
  "r124": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1505-109256"
  },
  "r125": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1252-109256"
  },
  "r126": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1707-109256"
  },
  "r127": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "23",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1757-109256"
  },
  "r128": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1500-109256"
  },
  "r129": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1278-109256"
  },
  "r13": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30)(a)(4))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r130": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "55",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e2626-109256"
  },
  "r131": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "60B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256"
  },
  "r132": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "60B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256"
  },
  "r133": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1337-109256"
  },
  "r134": {
   "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"
  },
  "r135": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257"
  },
  "r136": {
   "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"
  },
  "r137": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=6371337&loc=d3e3630-109257"
  },
  "r138": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=109243012&loc=SL65017193-207537"
  },
  "r139": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=120380238&loc=d3e3842-109258"
  },
  "r14": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r140": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "52",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=120380238&loc=d3e4984-109258"
  },
  "r141": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "260",
   "URI": "http://asc.fasb.org/topic&trid=2144383"
  },
  "r142": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=6828210&loc=d3e70191-108054"
  },
  "r143": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=6828210&loc=d3e70229-108054"
  },
  "r144": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055"
  },
  "r145": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055"
  },
  "r146": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r147": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r148": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r149": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r15": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r150": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r151": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r152": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599"
  },
  "r153": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599"
  },
  "r154": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599"
  },
  "r155": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599"
  },
  "r156": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "31",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599"
  },
  "r157": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599"
  },
  "r158": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599"
  },
  "r159": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599"
  },
  "r16": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r160": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599"
  },
  "r161": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599"
  },
  "r162": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "40",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599"
  },
  "r163": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "41",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599"
  },
  "r164": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "42",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599"
  },
  "r165": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121593590&loc=d3e4647-111522"
  },
  "r166": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522"
  },
  "r167": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524"
  },
  "r168": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524"
  },
  "r169": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(3)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524"
  },
  "r17": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.1)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r170": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(4)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524"
  },
  "r171": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(g)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524"
  },
  "r172": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524"
  },
  "r173": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524"
  },
  "r174": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953550-111524"
  },
  "r175": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(3)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524"
  },
  "r176": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(4)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524"
  },
  "r177": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524"
  },
  "r178": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524"
  },
  "r179": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524"
  },
  "r18": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.13)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r180": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524"
  },
  "r181": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953659-111524"
  },
  "r182": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=d3e5066-111524"
  },
  "r183": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "33",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524"
  },
  "r184": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "35",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL49126937-111524"
  },
  "r185": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524"
  },
  "r186": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524"
  },
  "r187": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524"
  },
  "r188": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121611835&loc=SL6953401-111524"
  },
  "r189": {
   "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"
  },
  "r19": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.14)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r190": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 6.L.1)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707"
  },
  "r191": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/subtopic&trid=2196772"
  },
  "r192": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=6378536&loc=d3e10092-111533"
  },
  "r193": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=109123552&loc=SL109123557-218513"
  },
  "r194": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(b)(1)(ii)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544"
  },
  "r195": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121585226&loc=d3e18845-111554"
  },
  "r196": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121553693&loc=d3e26610-111562"
  },
  "r197": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121553693&loc=d3e26853-111562"
  },
  "r198": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121553693&loc=SL6284422-111562"
  },
  "r199": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=SL6283291-111563"
  },
  "r2": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=121566466&loc=d3e6676-107765"
  },
  "r20": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r200": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563"
  },
  "r201": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(aa)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563"
  },
  "r202": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563"
  },
  "r203": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563"
  },
  "r204": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563"
  },
  "r205": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27198-111563"
  },
  "r206": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563"
  },
  "r207": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(aa)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563"
  },
  "r208": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563"
  },
  "r209": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563"
  },
  "r21": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.22(a)(1))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r210": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563"
  },
  "r211": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)(4)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563"
  },
  "r212": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563"
  },
  "r213": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=SL120269820-111563"
  },
  "r214": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=SL120269820-111563"
  },
  "r215": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=SL120269820-111563"
  },
  "r216": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=SL120269820-111563"
  },
  "r217": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=SL120269825-111563"
  },
  "r218": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=SL120269825-111563"
  },
  "r219": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27290-111563"
  },
  "r22": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r220": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27290-111563"
  },
  "r221": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(2)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27290-111563"
  },
  "r222": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27337-111563"
  },
  "r223": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=SL6284393-111563"
  },
  "r224": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27357-111563"
  },
  "r225": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=121645371&loc=d3e27357-111563"
  },
  "r226": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "320",
   "URI": "http://asc.fasb.org/topic&trid=2196928"
  },
  "r227": {
   "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"
  },
  "r228": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "323",
   "URI": "http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571"
  },
  "r229": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437"
  },
  "r23": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r230": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437"
  },
  "r231": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437"
  },
  "r232": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437"
  },
  "r233": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(1)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437"
  },
  "r234": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(2)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437"
  },
  "r235": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(3)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437"
  },
  "r236": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(4)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437"
  },
  "r237": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121599337&loc=SL82919244-210447"
  },
  "r238": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447"
  },
  "r239": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447"
  },
  "r24": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.28,29)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r240": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121599337&loc=SL82919253-210447"
  },
  "r241": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447"
  },
  "r242": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447"
  },
  "r243": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121599337&loc=SL82919230-210447"
  },
  "r244": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121599337&loc=SL82919230-210447"
  },
  "r245": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121647567&loc=SL82921830-210448"
  },
  "r246": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121647567&loc=SL82921833-210448"
  },
  "r247": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121647567&loc=SL82921835-210448"
  },
  "r248": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(d)(2)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121647567&loc=SL82921835-210448"
  },
  "r249": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121647567&loc=SL82921842-210448"
  },
  "r25": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r250": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "79",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448"
  },
  "r251": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "80",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121647567&loc=SL82922355-210448"
  },
  "r252": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454"
  },
  "r253": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)(1)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121582814&loc=SL82922888-210455"
  },
  "r254": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)(2)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121582814&loc=SL82922888-210455"
  },
  "r255": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121582814&loc=SL82922888-210455"
  },
  "r256": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121582814&loc=SL82922890-210455"
  },
  "r257": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121582814&loc=SL82922895-210455"
  },
  "r258": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121582814&loc=SL82922900-210455"
  },
  "r259": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121590138&loc=SL82922954-210456"
  },
  "r26": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r260": {
   "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"
  },
  "r261": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=120320667&loc=SL49117168-202975"
  },
  "r262": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "350",
   "URI": "http://asc.fasb.org/topic&trid=2144416"
  },
  "r263": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229"
  },
  "r264": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229"
  },
  "r265": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229"
  },
  "r266": {
   "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"
  },
  "r267": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "360",
   "URI": "http://asc.fasb.org/topic&trid=2155823"
  },
  "r268": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "440",
   "URI": "http://asc.fasb.org/extlink&oid=121559207&loc=d3e25336-109308"
  },
  "r269": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "440",
   "URI": "http://asc.fasb.org/extlink&oid=121559207&loc=d3e25336-109308"
  },
  "r27": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r270": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "440",
   "URI": "http://asc.fasb.org/topic&trid=2144648"
  },
  "r271": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349"
  },
  "r272": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=121557415&loc=d3e14615-108349"
  },
  "r273": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=121557415&loc=d3e14394-108349"
  },
  "r274": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349"
  },
  "r275": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=121557415&loc=d3e14453-108349"
  },
  "r276": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=121557415&loc=d3e14472-108349"
  },
  "r277": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349"
  },
  "r278": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "450",
   "URI": "http://asc.fasb.org/topic&trid=2127136"
  },
  "r279": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "460",
   "URI": "http://asc.fasb.org/extlink&oid=121555522&loc=d3e12021-110248"
  },
  "r28": {
   "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"
  },
  "r280": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "460",
   "URI": "http://asc.fasb.org/extlink&oid=121555522&loc=d3e12053-110248"
  },
  "r281": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(4)",
   "Topic": "460",
   "URI": "http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248"
  },
  "r282": {
   "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"
  },
  "r283": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(3)",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870"
  },
  "r284": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=99377297&loc=d3e10013-112621"
  },
  "r285": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "470",
   "URI": "http://asc.fasb.org/topic&trid=2208564"
  },
  "r286": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(CFRR 211.02)",
   "Topic": "480",
   "URI": "http://asc.fasb.org/extlink&oid=65877616&loc=d3e177068-122764"
  },
  "r287": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=65888546&loc=d3e21300-112643"
  },
  "r288": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21553-112644"
  },
  "r289": {
   "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"
  },
  "r29": {
   "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"
  },
  "r290": {
   "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"
  },
  "r291": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21484-112644"
  },
  "r292": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21488-112644"
  },
  "r293": {
   "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"
  },
  "r294": {
   "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"
  },
  "r295": {
   "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"
  },
  "r296": {
   "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=120397183&loc=d3e187085-122770"
  },
  "r297": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=121604090&loc=SL49130543-203045"
  },
  "r298": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045"
  },
  "r299": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "91",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=121551570&loc=SL49130690-203046-203046"
  },
  "r3": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(13))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r30": {
   "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"
  },
  "r300": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(g)(2)",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=113356391&loc=SL49131195-203048"
  },
  "r301": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(i)",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=113356391&loc=SL49131195-203048"
  },
  "r302": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(i)(2)",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=113356391&loc=SL49131195-203048"
  },
  "r303": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(j)",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=113356391&loc=SL49131195-203048"
  },
  "r304": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "710",
   "URI": "http://asc.fasb.org/topic&trid=2127225"
  },
  "r305": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "712",
   "URI": "http://asc.fasb.org/topic&trid=2197446"
  },
  "r306": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(i)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r307": {
   "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"
  },
  "r308": {
   "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"
  },
  "r309": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r31": {
   "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"
  },
  "r310": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)(A)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r311": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)(B)",
   "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)(02)(C)",
   "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": "(d)(iv)(03)",
   "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": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "80",
   "Subparagraph": "(d)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947"
  },
  "r317": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "80",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948"
  },
  "r318": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "715",
   "URI": "http://asc.fasb.org/topic&trid=2235017"
  },
  "r319": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901"
  },
  "r32": {
   "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"
  },
  "r320": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901"
  },
  "r321": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901"
  },
  "r322": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(3)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r323": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a),(g)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r324": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r325": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(iv)(3)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r326": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)(i)-(ii)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r327": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)(iii)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r328": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)(iii)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r329": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)(iii)(3)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r33": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=99393222&loc=SL20226024-175313"
  },
  "r330": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r331": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(i)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r332": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r333": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r334": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r335": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r336": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r337": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r338": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(f)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r339": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(f)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r34": {
   "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"
  },
  "r340": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(g)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r341": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(g)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r342": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "718",
   "URI": "http://asc.fasb.org/topic&trid=2228938"
  },
  "r343": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32672-109319"
  },
  "r344": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "740"
  },
  "r345": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "740"
  },
  "r346": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)(2)",
   "Topic": "740"
  },
  "r347": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)(3)",
   "Topic": "740"
  },
  "r348": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(1)",
   "Topic": "740"
  },
  "r349": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(2)",
   "Topic": "740"
  },
  "r35": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=99393222&loc=SL20226006-175313"
  },
  "r350": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(3)",
   "Topic": "740"
  },
  "r351": {
   "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"
  },
  "r352": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=120385591&loc=d3e39076-109324"
  },
  "r353": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=120385591&loc=d3e38679-109324"
  },
  "r354": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(d)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=120385591&loc=d3e38679-109324"
  },
  "r355": {
   "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"
  },
  "r356": {
   "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"
  },
  "r357": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116870748&loc=SL6758485-165988"
  },
  "r358": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116870748&loc=SL6758485-165988"
  },
  "r359": {
   "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"
  },
  "r36": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580"
  },
  "r360": {
   "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"
  },
  "r361": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bb)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=121559654&loc=d3e5710-111685"
  },
  "r362": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=121559654&loc=d3e5710-111685"
  },
  "r363": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "810",
   "URI": "http://asc.fasb.org/topic&trid=2197479"
  },
  "r364": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959"
  },
  "r365": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959"
  },
  "r366": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959"
  },
  "r367": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&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=121590274&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=121590274&loc=SL5618551-113959"
  },
  "r37": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(dd)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580"
  },
  "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=121590274&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=121590274&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=121590274&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=121590274&loc=SL5624163-113959"
  },
  "r374": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959"
  },
  "r375": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bb)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959"
  },
  "r376": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959"
  },
  "r377": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959"
  },
  "r378": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959"
  },
  "r379": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959"
  },
  "r38": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580"
  },
  "r380": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4CC",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL109998890-113959"
  },
  "r381": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624177-113959"
  },
  "r382": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624177-113959"
  },
  "r383": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624177-113959"
  },
  "r384": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624177-113959"
  },
  "r385": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4E",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=SL5624181-113959"
  },
  "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=121590274&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=121590274&loc=d3e41678-113959"
  },
  "r388": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121590274&loc=d3e41678-113959"
  },
  "r389": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "182",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121582272&loc=SL5629052-113961"
  },
  "r39": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580"
  },
  "r390": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121577181&loc=SL110061190-113977"
  },
  "r391": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "25",
   "Subparagraph": "(a)(1),(2)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121577467&loc=d3e76258-113986"
  },
  "r392": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "25",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121577467&loc=d3e76258-113986"
  },
  "r393": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121558989&loc=d3e80720-113993"
  },
  "r394": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "815",
   "URI": "http://asc.fasb.org/topic&trid=2229140"
  },
  "r395": {
   "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"
  },
  "r396": {
   "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"
  },
  "r397": {
   "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"
  },
  "r398": {
   "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"
  },
  "r399": {
   "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"
  },
  "r4": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(14))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r40": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(h)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580"
  },
  "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",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r402": {
   "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"
  },
  "r403": {
   "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"
  },
  "r404": {
   "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"
  },
  "r405": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=121572278&loc=d3e13433-108611"
  },
  "r406": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=121572278&loc=d3e13467-108611"
  },
  "r407": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=121572278&loc=d3e13476-108611"
  },
  "r408": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612"
  },
  "r409": {
   "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"
  },
  "r41": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580"
  },
  "r410": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32136-110900"
  },
  "r411": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(a)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r412": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(b)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r413": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(c)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r414": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(d)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r415": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r416": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=6450520&loc=d3e32583-110901"
  },
  "r417": {
   "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"
  },
  "r418": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399"
  },
  "r419": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399"
  },
  "r42": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580"
  },
  "r420": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399"
  },
  "r421": {
   "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"
  },
  "r422": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "840",
   "URI": "http://asc.fasb.org/extlink&oid=121616839&loc=d3e45280-112737"
  },
  "r423": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=121603541&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=121603541&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=121603541&loc=SL77918643-209977"
  },
  "r426": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980"
  },
  "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=121609121&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=121609121&loc=SL77918686-209980"
  },
  "r429": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(3)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980"
  },
  "r43": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=d3e640-108580"
  },
  "r430": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(4)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980"
  },
  "r431": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980"
  },
  "r432": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=121609121&loc=SL77918701-209980"
  },
  "r433": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "53",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971"
  },
  "r434": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/subtopic&trid=77888251"
  },
  "r435": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864"
  },
  "r436": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864"
  },
  "r437": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39599-107864"
  },
  "r438": {
   "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"
  },
  "r439": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(2)(i)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r44": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=d3e681-108580"
  },
  "r440": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(2)(ii)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r441": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r442": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r443": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r444": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r445": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r446": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r447": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r448": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r449": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(cc)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r45": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669686-108580"
  },
  "r450": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)(5)(ii)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r451": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r452": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r453": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r454": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r455": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r456": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r457": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719"
  },
  "r458": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719"
  },
  "r459": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728"
  },
  "r46": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=d3e689-108580"
  },
  "r460": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(b)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729"
  },
  "r461": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(c)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729"
  },
  "r462": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=109249958&loc=SL34722452-111729"
  },
  "r463": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(c)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=109249958&loc=SL34722452-111729"
  },
  "r464": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "50",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=6469459&loc=d3e122492-111745"
  },
  "r465": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "50",
   "Subparagraph": "(a)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745"
  },
  "r466": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "50",
   "Subparagraph": "(b)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745"
  },
  "r467": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122596-111746"
  },
  "r468": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(b)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122596-111746"
  },
  "r469": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(d)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122596-111746"
  },
  "r47": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL34724391-108580"
  },
  "r470": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746"
  },
  "r471": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746"
  },
  "r472": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746"
  },
  "r473": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746"
  },
  "r474": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(4)(i)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746"
  },
  "r475": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(4)(ii)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746"
  },
  "r476": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(5)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746"
  },
  "r477": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r478": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r479": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r48": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL34724394-108580"
  },
  "r480": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(4)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r481": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(5)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r482": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(6)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r483": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(a)(7)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r484": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(b)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r485": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(d)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r486": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(e)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r487": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(e)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r488": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Subparagraph": "(e)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746"
  },
  "r489": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "860",
   "URI": "http://asc.fasb.org/topic&trid=2197590"
  },
  "r49": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580"
  },
  "r490": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "910",
   "URI": "http://asc.fasb.org/extlink&oid=119991564&loc=SL119991595-234733"
  },
  "r491": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 11.L)",
   "Topic": "924",
   "URI": "http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856"
  },
  "r492": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "926",
   "URI": "http://asc.fasb.org/extlink&oid=120154821&loc=SL120154904-197079"
  },
  "r493": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "926",
   "URI": "http://asc.fasb.org/extlink&oid=120154821&loc=SL120154904-197079"
  },
  "r494": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "926",
   "URI": "http://asc.fasb.org/extlink&oid=120154821&loc=SL120154904-197079"
  },
  "r495": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(f)(1)",
   "Topic": "926",
   "URI": "http://asc.fasb.org/extlink&oid=120154821&loc=SL120154904-197079"
  },
  "r496": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(f)(2)",
   "Topic": "926",
   "URI": "http://asc.fasb.org/extlink&oid=120154821&loc=SL120154904-197079"
  },
  "r497": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(f)(3)",
   "Topic": "926",
   "URI": "http://asc.fasb.org/extlink&oid=120154821&loc=SL120154904-197079"
  },
  "r498": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "320",
   "Topic": "940",
   "URI": "http://asc.fasb.org/extlink&oid=35711157&loc=d3e42567-110969"
  },
  "r499": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "320",
   "Topic": "940",
   "URI": "http://asc.fasb.org/subtopic&trid=2176304"
  },
  "r5": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r50": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580"
  },
  "r500": {
   "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"
  },
  "r501": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(1))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r502": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(10)(1))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r503": {
   "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=120398452&loc=d3e534808-122878"
  },
  "r504": {
   "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=120398452&loc=d3e534808-122878"
  },
  "r505": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(13))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r506": {
   "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=120398452&loc=d3e534808-122878"
  },
  "r507": {
   "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=120398452&loc=d3e534808-122878"
  },
  "r508": {
   "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=120398452&loc=d3e534808-122878"
  },
  "r509": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.10(4))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r51": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580"
  },
  "r510": {
   "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=120398452&loc=d3e534808-122878"
  },
  "r511": {
   "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=120398452&loc=d3e534808-122878"
  },
  "r512": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.15(5))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r513": {
   "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=120398452&loc=d3e534808-122878"
  },
  "r514": {
   "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=120398452&loc=d3e534808-122878"
  },
  "r515": {
   "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=120398452&loc=d3e534808-122878"
  },
  "r516": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r517": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r518": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r519": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r52": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669625-108580"
  },
  "r520": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(26))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r521": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(27))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r522": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r523": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r524": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r525": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r526": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r527": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.13(h))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r528": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r529": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.14(b))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r53": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669625-108580"
  },
  "r530": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.14(d))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r531": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r532": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.2)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r533": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r534": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.7,8)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r535": {
   "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=120399700&loc=SL114874048-224260"
  },
  "r536": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "230",
   "Subparagraph": "(b)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=121551529&loc=d3e60009-112784"
  },
  "r537": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "230",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=121551529&loc=d3e60009-112784"
  },
  "r538": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "320",
   "Subparagraph": "(b)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120252992&loc=d3e62557-112803"
  },
  "r539": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "320",
   "Subparagraph": "(d)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120252992&loc=d3e62586-112803"
  },
  "r54": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=d3e557-108580"
  },
  "r540": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "320",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120252992&loc=d3e62586-112803"
  },
  "r541": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "320",
   "Subparagraph": "(d)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120252992&loc=SL120269850-112803"
  },
  "r542": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "320",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120252992&loc=SL120269850-112803"
  },
  "r543": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "320",
   "Topic": "942",
   "URI": "http://asc.fasb.org/subtopic&trid=2209399"
  },
  "r544": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "325",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75031641&loc=d3e63345-112809"
  },
  "r545": {
   "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"
  },
  "r546": {
   "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"
  },
  "r547": {
   "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=120400017&loc=d3e572229-122910"
  },
  "r548": {
   "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=120400017&loc=d3e572229-122910"
  },
  "r549": {
   "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=120400017&loc=d3e572229-122910"
  },
  "r55": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121640130&loc=d3e1436-108581"
  },
  "r550": {
   "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=120400017&loc=d3e572229-122910"
  },
  "r551": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(23)(a)(3))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r552": {
   "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=120400017&loc=d3e572229-122910"
  },
  "r553": {
   "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=120400017&loc=d3e572229-122910"
  },
  "r554": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(8))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r555": {
   "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=120400017&loc=d3e572229-122910"
  },
  "r556": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03.15(a))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r557": {
   "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=120400993&loc=SL114874131-224263"
  },
  "r558": {
   "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=120400993&loc=SL114874131-224263"
  },
  "r559": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(22))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r56": {
   "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=120395209&loc=SL114868656-224227"
  },
  "r560": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(23))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r561": {
   "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=120400993&loc=SL114874131-224263"
  },
  "r562": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(9))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r563": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04.3(a))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r564": {
   "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"
  },
  "r565": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Subparagraph": "(d)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121643868&loc=SL117782755-158439"
  },
  "r566": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13H",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "40",
   "Subparagraph": "(a)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121639165&loc=SL117783719-158441"
  },
  "r567": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29F",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "40",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121639165&loc=SL117819544-158441"
  },
  "r568": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(a)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r569": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(b)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r57": {
   "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=120395209&loc=SL114868664-224227"
  },
  "r570": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(e)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r571": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(f)(1)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r572": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(f)(2)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r573": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(1)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r574": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(2)(i)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r575": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(2)(ii)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r576": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(2)(iii)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r577": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(2)(iv)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r578": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(h)(1)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r579": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(h)(2)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r58": {
   "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=120395209&loc=SL114868664-224227"
  },
  "r580": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "80",
   "Subparagraph": "(e)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121641442&loc=d3e19393-158473"
  },
  "r581": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "220",
   "Subparagraph": "(k)",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=118262090&loc=SL114874205-224268"
  },
  "r582": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.6-07.2(a),(b),(c),(d))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=120401555&loc=SL114874292-224272"
  },
  "r583": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "320",
   "Topic": "946",
   "URI": "http://asc.fasb.org/subtopic&trid=2324412"
  },
  "r584": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "310",
   "Topic": "948",
   "URI": "http://asc.fasb.org/extlink&oid=120238483&loc=d3e48678-111004"
  },
  "r585": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "310",
   "Subparagraph": "(SX 210.12-29(Footnote 4))",
   "Topic": "948",
   "URI": "http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014"
  },
  "r586": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "310",
   "Subparagraph": "(SX 210.12-29)",
   "Topic": "948",
   "URI": "http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014"
  },
  "r587": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "360",
   "Subparagraph": "(d)",
   "Topic": "958",
   "URI": "http://asc.fasb.org/extlink&oid=120429125&loc=d3e99779-112916"
  },
  "r588": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "360",
   "Topic": "958",
   "URI": "http://asc.fasb.org/extlink&oid=120429125&loc=d3e99893-112916"
  },
  "r589": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "360",
   "Topic": "958",
   "URI": "http://asc.fasb.org/extlink&oid=120429125&loc=SL120174063-112916"
  },
  "r59": {
   "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=120395209&loc=SL114868664-224227"
  },
  "r590": {
   "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=120402810&loc=d3e638233-123024"
  },
  "r591": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b"
  },
  "r592": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "d1-1"
  },
  "r593": {
   "Name": "Form 10-Q",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "13",
   "Subsection": "a-13"
  },
  "r594": {
   "Name": "Forms 10-K, 10-Q, 20-F",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "13",
   "Subsection": "a-1-"
  },
  "r595": {
   "Name": "Regulation 12B",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b-2"
  },
  "r596": {
   "Name": "Regulation S-T",
   "Number": "232",
   "Publisher": "SEC",
   "Section": "405"
  },
  "r597": {
   "Footnote": "4",
   "Name": "Regulation S-X (SX)",
   "Number": "210",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "28"
  },
  "r598": {
   "Name": "Regulation S-X (SX)",
   "Number": "210",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "29"
  },
  "r599": {
   "Name": "Regulation S-X (SX)",
   "Number": "210",
   "Paragraph": "(m)",
   "Publisher": "SEC",
   "Section": "4",
   "Subparagraph": "(1)(iii)",
   "Subsection": "08"
  },
  "r6": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r60": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(24))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r61": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(25))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r62": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(b)(4))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r63": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.4)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r64": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.6)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r65": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "220",
   "URI": "http://asc.fasb.org/topic&trid=2134417"
  },
  "r66": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3151-108585"
  },
  "r67": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585"
  },
  "r68": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585"
  },
  "r69": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585"
  },
  "r7": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(20))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r70": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585"
  },
  "r71": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585"
  },
  "r72": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585"
  },
  "r73": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585"
  },
  "r74": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585"
  },
  "r75": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585"
  },
  "r76": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3367-108585"
  },
  "r77": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "21",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3461-108585"
  },
  "r78": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "24",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3521-108585"
  },
  "r79": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585"
  },
  "r8": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r80": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585"
  },
  "r81": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585"
  },
  "r82": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585"
  },
  "r83": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585"
  },
  "r84": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585"
  },
  "r85": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3044-108585"
  },
  "r86": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3095-108585"
  },
  "r87": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121583591&loc=d3e4297-108586"
  },
  "r88": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121583591&loc=d3e4304-108586"
  },
  "r89": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121583591&loc=d3e4313-108586"
  },
  "r9": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r90": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121583591&loc=d3e4332-108586"
  },
  "r91": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121583591&loc=SL98516268-108586"
  },
  "r92": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(d))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r93": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(g)(1)(ii))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r94": {
   "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=120395691&loc=d3e23780-122690"
  },
  "r95": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(m)(1)(iii))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r96": {
   "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=120395691&loc=d3e23780-122690"
  },
  "r97": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08.(h)(1)(i))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r98": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08.(m)(1)(i)(A))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r99": {
   "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=120395691&loc=d3e24072-122690"
  }
 },
 "version": "2.1"
}
