SECURITIZATIONS AND VARIABLE INTEREST ENTITIES (Details 9) (USD $)			3 Months Ended		12 Months Ended	3 Months Ended		6 Months Ended					3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Client intermediation	Mar. 31, 2014 Citi-administered asset-backed commercial paper conduits (ABCP) item	Dec. 31, 2013 Citi-administered asset-backed commercial paper conduits (ABCP)	Mar. 31, 2014 Citi-administered asset-backed commercial paper conduits (ABCP) Minimum	Mar. 31, 2014 Citi-administered asset-backed commercial paper conduits (ABCP) Maximum	Jun. 30, 2013 Citi-administered asset-backed consolidated commercial paper conduits (ABCP)	Mar. 31, 2014 Citi-administered asset-backed consolidated commercial paper conduits (ABCP)	Dec. 31, 2013 Citi-administered asset-backed consolidated commercial paper conduits (ABCP)	Mar. 31, 2014 Municipal securities tender option bond trusts (TOBs)	Dec. 31, 2013 Municipal securities tender option bond trusts (TOBs)	Mar. 31, 2014 Municipal securities tender option bond trusts (TOBs) Maximum
Classification of Other Securitization Details
Purchased assets outstanding under conduits				$ 32,000,000,000	$ 32,000,000,000
Incremental funding commitments with clients				14,000,000,000	13,500,000,000
Weighted average remaining life of commercial paper issued by conduits				67 days	67 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									2,400,000,000	2,300,000,000
Commercial paper	14,874,000,000	17,878,000,000							14,600,000,000	13,900,000,000
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											226,000,000	230,000,000
Liquidity agreements, customer TOB trust											3,600,000,000	3,900,000,000
Liquidity agreements, other trusts											7,500,000,000	5,400,000,000
Notional amount of offsetting reimbursement agreements											2,600,000,000	2,800,000,000
Floater inventory held by entity											93,000,000	176,000,000
Trust assets	0
Proceeds from new securitizations			$ 900,000,000