BUSINESS SEGMENTS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment reporting information
Total revenues, net of interest expense	$ 20,479	$ 18,387	$ 40,706	$ 37,508
Provision (benefit) for income taxes	2,127	718	3,697	1,715
Income (loss) from continuing operations	4,188	2,979	8,119	6,024
Pretax provisions (credits) for credit losses and for benefits and claims	2,024	2,696	4,483	5,596
Total Citicorp and Corporate/Other
Segment reporting information
Total revenues, net of interest expense	19,387	17,449	38,713	35,688
Provision (benefit) for income taxes	2,464	1,331	4,593	2,975
Income (loss) from continuing operations	4,757	3,888	9,477	7,950
Citicorp | North America
Segment reporting information
Total revenues, net of interest expense	8,300	7,700	17,000	15,000
Citicorp | EMEA
Segment reporting information
Total revenues, net of interest expense	3,500	2,900	6,600	6,100
Citicorp | Latin America
Segment reporting information
Total revenues, net of interest expense	3,500	3,300	7,100	6,600
Citicorp | Asia
Segment reporting information
Total revenues, net of interest expense	4,000	3,800	8,000	7,800
Global Consumer Banking
Segment reporting information
Regional business	4		4
Total revenues, net of interest expense	9,711	9,507	19,460	19,228
Provision (benefit) for income taxes	1,022	1,017	1,998	2,016
Income (loss) from continuing operations	1,955	1,971	3,872	4,131
Pretax provisions (credits) for credit losses and for benefits and claims	1,600	1,300	3,300	2,800
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
Total revenues, net of interest expense	9,573	8,238	19,157	16,285
Provision (benefit) for income taxes	1,476	760	2,882	1,398
Income (loss) from continuing operations	3,190	2,364	6,315	4,597
Pretax provisions (credits) for credit losses and for benefits and claims	(30)	135	35	224
Corporate/Other
Segment reporting information
Total revenues, net of interest expense	103	(296)	96	175
Provision (benefit) for income taxes	(34)	(446)	(287)	(439)
Income (loss) from continuing operations	(388)	(447)	(710)	(778)
Citi Holdings
Segment reporting information
Total revenues, net of interest expense	1,092	938	1,993	1,820
Provision (benefit) for income taxes	(337)	(613)	(896)	(1,260)
Income (loss) from continuing operations	(569)	(909)	(1,358)	(1,926)
Pretax provisions (credits) for credit losses and for benefits and claims	$ 500	$ 1,200	$ 1,200	$ 2,600