Line of Credit Facility, Maximum Borrowing Capacity, Portion Not Extended

No definition available.

Name:	cit_LineofCreditFacilityMaximumBorrowingCapacityPortionNotExtended
Namespace Prefix:	cit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Tier Two Risk Based Capital, Additional Common Equity Distributions Approved

+ References

No definition available.

+ Details

Name:	cit_TierTwoRiskBasedCapitalAdditionalCommonEquityDistributionsApproved
Namespace Prefix:	cit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Tier Two Risk Based Capital, Additional Subordinated Debt Approved

+ References

No definition available.

+ Details

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Namespace Prefix:	cit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Tier Two Risk Based Capital, Subordinated Debt Issuance Required for Additional Common Equity Issuance Approved

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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Period Type:	duration

- Details

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- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
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Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=cit_RevolvingCreditFacilityNotLetterofCreditMember
Namespace Prefix:
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- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
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Subsequent Events (Details) - USD ($)	Feb. 01, 2018	Feb. 16, 2018	Feb. 15, 2018	Dec. 31, 2017	Feb. 28, 2017	Jan. 31, 2017	Dec. 31, 2016
Subsequent Event
Subsequent Event [Line Items]
Additional Tier 2 qualifying subordinated debt approved	$ 400,000,000
Additional Tier 2 common equity distribution approved	800,000,000
Tier 2 qualifying subordinated debt required for additional common equity distribution	$ 400,000,000
Revolving Credit Facility
Subsequent Event [Line Items]
Total commitment				$ 750,000,000	$ 1,400,000,000	$ 1,500,000,000
Outstanding borrowings				$ 0			$ 0
Revolving Credit Facility \| Subsequent Event
Subsequent Event [Line Items]
Total commitment		$ 500,000,000	$ 750,000,000
Commitment not extended		42,000,000
Revolving Credit Facility, Not Letter of Credit \| Subsequent Event
Subsequent Event [Line Items]
Total commitment		375,000,000
Outstanding borrowings		0
Letter of Credit \| Subsequent Event
Subsequent Event [Line Items]
Total commitment		125,000,000
Outstanding borrowings		$ 55,000,000