BUSINESS SEGMENTS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment reporting information
Total revenues, net of interest expense	$ 17,880	$ 13,703	$ 58,586	$ 51,211
Provision (benefit) for income taxes	1,080	(1,494)	4,777	221
Income (loss) from continuing operations	3,186	485	11,305	6,509
Pretax provisions (credits) for credit losses and for benefits and claims	1,959	2,620	6,442	8,216
Total Citicorp and Corporate/Other
Segment reporting information
Total revenues, net of interest expense	16,628	17,382	55,341	53,070
Provision (benefit) for income taxes	1,219	973	5,812	3,948
Income (loss) from continuing operations	3,284	4,038	12,761	11,988
Citicorp | North America
Segment reporting information
Total revenues, net of interest expense	7,200	7,600	24,200	22,600
Citicorp | EMEA
Segment reporting information
Total revenues, net of interest expense	2,500	2,700	9,100	8,800
Citicorp | Latin America
Segment reporting information
Total revenues, net of interest expense	3,400	3,400	10,400	10,000
Citicorp | Asia
Segment reporting information
Total revenues, net of interest expense	3,500	3,700	11,500	11,500
Global Consumer Banking
Segment reporting information
Regional business	4		4
Total revenues, net of interest expense	9,235	9,915	28,695	29,143
Provision (benefit) for income taxes	850	1,038	2,848	3,054
Income (loss) from continuing operations	1,626	2,107	5,498	6,238
Pretax provisions (credits) for credit losses and for benefits and claims	1,700	1,500	5,000	4,300
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	7,362	7,466	26,519	23,751
Provision (benefit) for income taxes	633	622	3,515	2,020
Income (loss) from continuing operations	1,795	2,007	8,110	6,604
Pretax provisions (credits) for credit losses and for benefits and claims	139	(32)	174	192
Corporate/Other
Segment reporting information
Total revenues, net of interest expense	31	1	127	176
Provision (benefit) for income taxes	(264)	(687)	(551)	(1,126)
Income (loss) from continuing operations	(137)	(76)	(847)	(854)
Citi Holdings
Segment reporting information
Total revenues, net of interest expense	1,252	(3,679)	3,245	(1,859)
Provision (benefit) for income taxes	(139)	(2,467)	(1,035)	(3,727)
Income (loss) from continuing operations	(98)	(3,553)	(1,456)	(5,479)
Pretax provisions (credits) for credit losses and for benefits and claims	$ 100	$ 1,200	$ 1,300	$ 3,700