PRINCIPAL TRANSACTIONS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Principal transactions revenue
Principal transactions revenue	$ 2,447	$ 1,931
Interest rate contracts
Principal transactions revenue
Principal transactions revenue	1,482	791
Foreign exchange contracts
Principal transactions revenue
Principal transactions revenue	431	754
Equity contracts
Principal transactions revenue
Principal transactions revenue	158	342
Commodity and other contracts
Principal transactions revenue
Principal transactions revenue	116	(21)
Credit derivatives
Principal transactions revenue
Principal transactions revenue	260	65
Citicorp
Principal transactions revenue
Principal transactions revenue	2,484	2,052
Global Consumer Banking
Principal transactions revenue
Principal transactions revenue	211	256
Institutional Clients Group
Principal transactions revenue
Principal transactions revenue	2,415	1,916
Corporate/Other
Principal transactions revenue
Principal transactions revenue	(142)	(120)
Citi Holdings
Principal transactions revenue
Principal transactions revenue	(37)	(121)
Local Consumer Lending
Principal transactions revenue
Principal transactions revenue	(6)	(23)
Brokerage and Asset Management
Principal transactions revenue
Principal transactions revenue	(5)	5
Special Asset Pool
Principal transactions revenue
Principal transactions revenue	$ (26)	$ (103)