Contingencies line items

No definition available.

Name:	cit_ContingenciesLineItems
Namespace Prefix:	cit_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Loss Contingency, Number Of Current Employees That May File Similar Lawsuits

+ References

No definition available.

+ Details

Name:	cit_LossContingencyNumberOfCurrentEmployeesThatMayFileSimilarLawsuits
Namespace Prefix:	cit_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Loss Contingency, Period Of Statute Of Limitations

+ References

No definition available.

+ Details

Name:	cit_LossContingencyPeriodOfStatuteOfLimitations
Namespace Prefix:	cit_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

+ References

No definition available.

+ Details

Name:	us-gaap_ContractualObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount awarded to other party in judgment or settlement of litigation.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementAmountAwardedToOtherParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The total number of new claims filed pertaining to a loss contingency during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

+ Details

Name:	us-gaap_LossContingencyNewClaimsFiledNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The difference between the maximum amount of estimated loss and the amount recorded as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 05
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6395354&loc=d3e12631-108344

+ Details

Name:	us-gaap_LossContingencyRangeOfPossibleLossPortionNotAccrued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77896938&loc=d3e25336-109308

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_IndemnificationGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=cit_OcwenLoanServicingLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=cit_BrazilianIndemnificationClaimsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationStatusAxis=us-gaap_PendingLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=cit_HUDOIGInvestigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_UnfavorableRegulatoryActionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationStatusAxis=us-gaap_SettledLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=cit_MortgageServicingConsentOrdersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Contingencies (Narrative) (Details) $ in Millions		9 Months Ended	12 Months Ended
Contingencies (Narrative) (Details) $ in Millions	May 16, 2017 USD ($)	Sep. 30, 2017 USD ($) employee labor_lawsuit	Dec. 31, 2014 USD ($)	Feb. 28, 2017 USD ($)
Maximum
Contingencies [Line Items]
Amount of losses in excess of established reserves and insurance related to those matters		$ 90.0
Indemnification Agreement \| Ocwen Loan Servicing LLC
Contingencies [Line Items]
Indemnification obligation		56.0
Indemnification Agreement \| Ocwen Loan Servicing LLC \| Maximum
Contingencies [Line Items]
Aggregate amount of claims				$ 150.0
Indemnification obligation		$ 150.0
Brazilian Indemnification Claims \| Indemnification Agreement \| Pending Litigation
Contingencies [Line Items]
Number of labor lawsuits \| labor_lawsuit		30
Number of current employees \| employee		45
Period employee/ independent contractor can recover damages for employment related claims		5 years
HUD OIG Investigation \| Unfavorable Regulatory Action \| Settled Litigation
Contingencies [Line Items]
Amount of settlement	$ 89.0
Mortgage Servicing Consent Orders \| Unfavorable Regulatory Action \| Pending Litigation \| Maximum
Contingencies [Line Items]
Amount of settlement			$ 12.7