SECURITIZATIONS AND VARIABLE INTEREST ENTITIES (Details 9) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2012 D	Dec. 31, 2011 D
Classification of Other Securitization Details
Commercial paper	$ 21,034,000,000	21,286,000,000
Citi-administered asset-backed commercial paper conduits (ABCP)
Classification of Other Securitization Details
Weighted average life of commercial paper issued by conduits (in days)	35	37
Floor price of conduit's assets	200,000,000
Letters of credit provided to conduits	1,700,000,000
Notional exposure under program-wide liquidity agreement	600,000,000
Assets held by unconsolidated government guaranteed loan conduit	10,500,000,000
Citi-administered asset-backed commercial paper conduits (ABCP) | Maximum
Classification of Other Securitization Details
Weighted average life of commercial paper (in days)	45
Letters of credit as percentage of conduit assets	10.00%
Citi-administered asset-backed commercial paper conduits (ABCP) | Minimum
Classification of Other Securitization Details
Weighted average life of commercial paper (in days)	25
Letters of credit as percentage of conduit assets	8.00%
Citi-administered asset-backed consolidated commercial paper conduits (ABCP)
Classification of Other Securitization Details
Commercial paper	4,600,000,000
Citi-administered asset-backed unconsolidated commercial paper conduits (ABCP)
Classification of Other Securitization Details
Commercial paper	199,000,000
Collateralized debt obligations (CDOs)
Classification of Other Securitization Details
Commercial paper issuance, description of variable rate basis	LIBOR
Collateralized debt obligations (CDOs) | Maximum
Classification of Other Securitization Details
Commercial paper issuance, limit on LIBOR variable rate (in basis points)	40
Collateralized debt obligations (CDOs) | Minimum
Classification of Other Securitization Details
Commercial paper issuance, limit on LIBOR variable rate (in basis points)	35
Municipal securities tender option bond trusts (TOBs)
Classification of Other Securitization Details
Percentage of maximum residuals to total trust funding	25.00%
Municipal bonds owned by trusts, that have credit guarantee provided by the Company	240,000,000
Liquidity agreements, customer TOB trust	5,800,000,000
Percentage of minimum residual owned by customer to bond value, remaining exposure	25.00%
Notional amount of offsetting reimbursement agreements	4,200,000,000
Floater inventory held by entity	$ 525,000,000