BUSINESS SEGMENTS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Segment reporting information
Revenues, net of interest expense	$ 18,642	$ 20,622	$ 38,048	$ 40,348
Provision (benefit) for income taxes	715	967	1,721	2,152
Income (loss) from continuing operations	2,987	3,332	6,049	6,363
Pretax provisions (credits) for credit losses and for benefits and claims	2,806	3,387	5,825	6,571
North America
Segment reporting information
Revenues, net of interest expense	7,700	7,700	14,900	15,600
EMEA
Segment reporting information
Revenues, net of interest expense	2,900	3,000	6,100	6,300
Latin America
Segment reporting information
Revenues, net of interest expense	3,500	3,500	7,200	6,800
Asia
Segment reporting information
Revenues, net of interest expense	3,800	3,800	7,800	7,400
Citicorp
Segment reporting information
Revenues, net of interest expense	17,983	17,952	36,015	36,090
Provision (benefit) for income taxes	1,769	1,584	3,408	3,521
Income (loss) from continuing operations	4,333	4,077	8,731	8,544
Global Consumer Banking
Segment reporting information
Revenues, net of interest expense	9,771	9,793	19,785	19,347
Provision (benefit) for income taxes	1,022	881	2,037	1,746
Income (loss) from continuing operations	1,990	2,019	4,178	3,939
Pretax provisions (credits) for credit losses and for benefits and claims	1,400	1,500	3,000	3,200
Institutional Clients Group
Segment reporting information
Number of countries where the entity provides a broad range of banking and financial products and services	100		100
Revenues, net of interest expense	8,212	8,159	16,230	16,743
Provision (benefit) for income taxes	747	703	1,371	1,775
Income (loss) from continuing operations	2,343	2,058	4,553	4,605
Pretax provisions (credits) for credit losses and for benefits and claims	135	86	224	(94)
Corporate/Other
Segment reporting information
Revenues, net of interest expense	(265)	263	235	202
Provision (benefit) for income taxes	(435)	(216)	(418)	(446)
Income (loss) from continuing operations	(427)	(134)	(739)	(613)
Total Citicorp and Corporate/Other
Segment reporting information
Revenues, net of interest expense	17,718	18,215	36,250	36,292
Provision (benefit) for income taxes	1,334	1,368	2,990	3,075
Income (loss) from continuing operations	3,906	3,943	7,992	7,391
Citi Holdings
Segment reporting information
Revenues, net of interest expense	924	2,407	1,798	4,056
Provision (benefit) for income taxes	(619)	(401)	(1,269)	(923)
Income (loss) from continuing operations	(919)	(611)	(1,943)	(1,568)
Pretax provisions (credits) for credit losses and for benefits and claims	$ 1,200	$ 1,800	$ 2,600	$ 3,500