BUSINESS SEGMENTS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segment reporting information
Total revenues, net of interest expense	$ 20,491	$ 19,406
Provision (benefit) for income taxes	1,588	1,006
Income (loss) from continuing operations	3,965	3,062
Pretax provisions (credits) for credit losses and for benefits and claims	2,540	3,019
Total Citicorp and Corporate/Other
Segment reporting information
Total revenues, net of interest expense	19,590	18,524
Provision (benefit) for income taxes	2,147	1,653
Income (loss) from continuing operations	4,754	4,079
Citicorp | North America
Segment reporting information
Total revenues, net of interest expense	8,700	7,300
Citicorp | EMEA
Segment reporting information
Total revenues, net of interest expense	3,100	3,200
Citicorp | Latin America
Segment reporting information
Total revenues, net of interest expense	3,800	3,600
Citicorp | Asia
Segment reporting information
Total revenues, net of interest expense	4,000	4,000
Global Consumer Banking
Segment reporting information
Regional business	4
Total revenues, net of interest expense	10,013	10,006
Provision (benefit) for income taxes	994	1,008
Income (loss) from continuing operations	1,951	2,177
Pretax provisions (credits) for credit losses and for benefits and claims	1,700	1,600
Institutional Clients Group
Segment reporting information
Number of countries where the entity provides a broad range of banking and financial products and services	100
Total revenues, net of interest expense	9,584	8,047
Provision (benefit) for income taxes	1,406	638
Income (loss) from continuing operations	3,125	2,233
Pretax provisions (credits) for credit losses and for benefits and claims	65	89
Corporate/Other
Segment reporting information
Total revenues, net of interest expense	(7)	471
Provision (benefit) for income taxes	(253)	7
Income (loss) from continuing operations	(322)	(331)
Citi Holdings
Segment reporting information
Total revenues, net of interest expense	901	882
Provision (benefit) for income taxes	(559)	(647)
Income (loss) from continuing operations	(789)	(1,017)
Pretax provisions (credits) for credit losses and for benefits and claims	$ 700	$ 1,300