SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Credit Card Securitizations (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Securitized credit card receivables
Gains (losses) recognized on the securitization	$ 0
Ownership interests in principal amount of trust credit card receivables
Sold to investors via trust-issued securities	0
Retained by Citigroup via non-certificated interests	0
Citicorp
Ownership interests in principal amount of trust credit card receivables
Sold to investors via trust-issued securities	37,000,000,000	32,300,000,000
Retained by Citigroup as trust-issued securities	10,100,000,000	8,100,000,000
Retained by Citigroup via non-certificated interests	14,200,000,000	12,100,000,000
Total ownership interests in principal amount of trust credit card receivables	61,300,000,000	52,500,000,000
Citicorp \| Credit card securitizations
Cash Flows Between Transferor and Transferee
Proceeds from new securitizations	12,500,000,000	11,500,000,000	500,000,000
Pay down of maturing notes	(7,800,000,000)	(2,100,000,000)	(20,400,000,000)
Citi Holdings
Ownership interests in principal amount of trust credit card receivables
Sold to investors via trust-issued securities		0
Retained by Citigroup as trust-issued securities	0	1,300,000,000
Retained by Citigroup via non-certificated interests		0
Total ownership interests in principal amount of trust credit card receivables	0	1,300,000,000
Citi Holdings \| Credit card securitizations
Cash Flows Between Transferor and Transferee
Proceeds from new securitizations	100,000,000	200,000,000	1,700,000,000
Pay down of maturing notes	$ 0	$ (100,000,000)	$ (100,000,000)

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The payment of maturing notes related to securitizations.

+ References

No definition available.

+ Details

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- Definition

This element represents the ownership interests in principal amount of trust credit card receivables sold to investors via trust-issued securities.

+ References

No definition available.

+ Details

Name:	c_PortionOfPrincipalAmountOutstandingOfSecuritizedAssetsAndAnyOtherFinancialAssetsManagedTogetherSoldToInvestorsViaTrustCreditCardReceivables
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Balance Type:	debit
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- Definition

This element represents the ownership interests in principal amount of trust credit card receivables retained by the reporting entity via non-certificated interests.

+ References

No definition available.

+ Details

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- Definition

This element represents the ownership interests in principal amount of trust credit card receivables retained by the reporting entity as trust-issued securities.

+ References

No definition available.

+ Details

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- Details

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- Definition

This element represents the principal amount of credit card receivables held in trusts.

+ References

No definition available.

+ Details

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- Definition

Cash Flows between a transferor and a transferee attributable to newly transferred assets related to either a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction (including, but not limited to, servicing, recourse, and restrictions on transferor's interests in the transferred financial assets).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph b

-URI http://asc.fasb.org/extlink&oid=13989330&loc=d3e107207-111719

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- Definition

A gain (loss) realized on a transfer, accounted for as a sale, of all or a portion of financial assets in which the transferor surrenders control and receives consideration other than a beneficial interest in the assets transferred. Reflects the amount of sales proceeds in excess of, or deficient from, the sum of the carrying amounts of transferred financial assets plus transaction costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7,9)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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