SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Funding, Liquidity Facilities and Subordinated Interests (Details) (USD $) In Billions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Funding, Liquidity Facilities and Subordinated Interests
Number of trusts to hold securitized credit card receivables	2c_SecuritizationTrustNumber
Citibank Credit Card Master Trust (Master Trust)
Funding, Liquidity Facilities and Subordinated Interests
Weighted average maturity of term notes	2 years 8 months	2 years 10 months 5 days
Term notes issued to third parties	$ 33.1	$ 35.7
Term notes retained by Citigroup affiliates	7.6	8.2
Total Trust liabilities	40.7	43.9
Citibank OMNI Master Trust (Omni Trust)
Funding, Liquidity Facilities and Subordinated Interests
Weighted average maturity of term notes	1 year 7 months	1 year 11 months
Term notes issued to third parties	1.3	1.3
Term notes retained by Citigroup affiliates	1.9	1.9
Total Trust liabilities	$ 3.2	$ 3.2

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The par value of liabilities of the credit card receivables securitization trust.

No definition available.

Represents the number of securitization trusts established to hold in trust a specific type of securitized receivables.

No definition available.

Name:	c_SecuritizationTrustNumber
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The par value of liabilities of the credit card receivables securitization trust related to term notes issued to third parties.

No definition available.

Name:	c_TermNotesIssuedToThirdParties
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The par value of liabilities of the credit card receivables securitization trust related to term notes retained by affiliates of the entity.

No definition available.

Name:	c_TermNotesRetainedByAffiliates
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This element represents the weighted average maturity of the term notes.

No definition available.

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Name:	us-gaap_StatementBusinessSegmentsAxis=c_CitibankCreditCardMasterTrustMember
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Name:	us-gaap_StatementBusinessSegmentsAxis=c_CitibankOMNIMasterTrustMember
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