BUSINESS SEGMENTS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Segment reporting information
Revenues, net of interest expense	$ 20,622	$ 22,071	$ 40,348	$ 47,492
Provision (benefit) for income taxes	967	812	2,152	1,848
Income (loss) from continuing operations	3,332	2,728	6,363	6,977
Pretax provisions (credits) for credit losses and for benefits and claims	3,387	6,665	6,571	15,283
Citicorp
Segment reporting information
Revenues, net of interest expense	16,348	16,489	32,852	35,011
Provision (benefit) for income taxes	1,353	1,247	3,053	3,266
Income (loss) from continuing operations	3,668	3,739	7,763	8,828
Regional Consumer Banking
Segment reporting information
Revenues, net of interest expense	8,214	8,032	16,156	16,114
Provision (benefit) for income taxes	650	317	1,275	524
Income (loss) from continuing operations	1,609	1,139	3,154	2,112
Pretax provisions (credits) for credit losses and for benefits and claims	1,200	2,500	2,500	5,400
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	8,134	8,457	16,696	18,897
Provision (benefit) for income taxes	703	930	1,778	2,742
Income (loss) from continuing operations	2,059	2,600	4,609	6,716
Pretax provisions (credits) for credit losses and for benefits and claims	84	(200)	(98)	(300)
Citi Holdings
Segment reporting information
Revenues, net of interest expense	4,011	4,919	7,294	11,469
Provision (benefit) for income taxes	(148)	(650)	(412)	(1,596)
Income (loss) from continuing operations	(168)	(1,204)	(715)	(2,079)
Pretax provisions (credits) for credit losses and for benefits and claims	2,100	4,300	4,200	10,100
Corporate/Other
Segment reporting information
Revenues, net of interest expense	263	663	202	1,012
Provision (benefit) for income taxes	(238)	215	(489)	178
Income (loss) from continuing operations	(168)	193	(685)	228
In North America Offices
Segment reporting information
Revenues, net of interest expense	6,100	7,000	12,400	14,900
EMEA
Segment reporting information
Revenues, net of interest expense	2,900	3,000	6,200	6,700
Latin America
Segment reporting information
Revenues, net of interest expense	3,500	3,000	6,800	6,100
Asia
Segment reporting information
Revenues, net of interest expense	$ 3,800	$ 3,500	$ 7,500	$ 7,300