SECURITIZATIONS AND VARIABLE INTEREST ENTITIES (Details 9) (USD $)			9 Months Ended	12 Months Ended	9 Months Ended		6 Months Ended						9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Citi-administered asset-backed commercial paper conduits (ABCP) item	Dec. 31, 2012 Citi-administered asset-backed commercial paper conduits (ABCP)	Sep. 30, 2013 Citi-administered asset-backed commercial paper conduits (ABCP) Minimum	Sep. 30, 2013 Citi-administered asset-backed commercial paper conduits (ABCP) Maximum	Jun. 30, 2013 Citi-administered asset-backed consolidated commercial paper conduits (ABCP)	Sep. 30, 2013 Citi-administered asset-backed consolidated commercial paper conduits (ABCP)	Dec. 31, 2012 Citi-administered asset-backed consolidated commercial paper conduits (ABCP)	Sep. 30, 2013 Citi-administered asset-backed unconsolidated commercial paper conduits (ABCP)	Sep. 30, 2013 Municipal securities tender option bond trusts (TOBs)	Dec. 31, 2012 Municipal securities tender option bond trusts (TOBs)	Sep. 30, 2013 Municipal securities tender option bond trusts (TOBs) Maximum
Classification of Other Securitization Details
Purchased assets outstanding under conduits			$ 28,000,000,000	$ 30,000,000,000
Incremental funding commitments with clients			16,000,000,000	14,000,000,000
Weighted average life of commercial paper					30 days	55 days
Weighted average life of commercial paper issued by conduits			47 days	38 days
Number of conduit which holds only loans that are fully guaranteed primarily by AAA-rated government agencies			1
Letters of credit as percentage of conduit assets					8.00%	10.00%
Floor price of conduit's assets					200,000,000
Letters of credit provided to conduits								1,900,000,000	2,100,000,000
Commercial paper	17,897,000,000	11,470,000,000	10,500,000,000	11,700,000,000				0		0
Increase in the amount of assets due to consolidation of loan because of changes in the primary risks and design of the conduit							7,000,000,000
Increase in the amount of liabilities due to consolidation of loan because of changes in the primary risks and design of the conduit							7,000,000,000
Net pretax gain due to consolidation of loan because of changes in the primary risks and design of the conduit							40,000,000
The threshold ownership percentage on Residual value of customers TOBs for which the reimbursement agreement applied													25.00%
Municipal bonds owned by trusts, that have credit guarantee provided by the Company											229,000,000	184,000,000
Liquidity agreements, customer TOB trust											4,200,000,000	4,900,000,000
Liquidity agreements, other trusts											6,300,000,000	6,400,000,000
Notional amount of offsetting reimbursement agreements											3,000,000,000	3,600,000,000
Floater inventory held by entity											213,000,000	203,000,000
Trust assets	$ 0