BUSINESS SEGMENTS (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015 USD ($) business market country	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) business market country	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Segment reporting information
Number of markets | market		11		11
Revenues, net of interest expense	[1]	$ 18,692	$ 19,689	$ 57,898	$ 59,320
Provision for income taxes		1,881	2,068	6,037	6,120
Income (loss) from continuing operations		4,306	2,916	13,981	7,121
Identifiable assets		1,808,356		1,808,356		$ 1,842,181
Provisions for credit losses and for benefits and claims		1,836	1,750	5,399	5,454
Operating Segments | Citicorp
Segment reporting information
Revenues, net of interest expense		17,275	17,619	52,974	53,275
Provision for income taxes		1,791	1,994	5,634	6,110
Income (loss) from continuing operations		4,275	2,700	13,640	10,679
Identifiable assets		1,698,000		1,698,000		1,713,000
Operating Segments | Global Consumer Banking and Institutional Clients Group | North America
Segment reporting information
Revenues, net of interest expense		8,100	8,200	24,400	24,400
Operating Segments | Global Consumer Banking and Institutional Clients Group | EMEA
Segment reporting information
Revenues, net of interest expense		2,700	2,500	8,500	8,400
Operating Segments | Global Consumer Banking and Institutional Clients Group | Latin America
Segment reporting information
Revenues, net of interest expense		3,000	3,200	8,900	9,700
Operating Segments | Global Consumer Banking and Institutional Clients Group | Asia
Segment reporting information
Revenues, net of interest expense		$ 3,300	3,600	$ 10,400	10,400
Operating Segments | Global Consumer Banking
Segment reporting information
Regional business | business		4		4
Revenues, net of interest expense		$ 8,460	9,201	$ 25,671	26,989
Provision for income taxes		919	995	2,644	2,539
Income (loss) from continuing operations		1,682	1,894	5,037	5,131
Identifiable assets		388,000		388,000		406,000
Provisions for credit losses and for benefits and claims		$ 1,400	1,300	$ 4,300	4,400
Operating Segments | Institutional Clients Group
Segment reporting information
Number of countries where the entity provides a broad range of banking and financial products and services | country		100		100
Revenues, net of interest expense		$ 8,597	8,336	$ 26,503	25,892
Provision for income taxes		1,186	1,102	3,861	3,628
Income (loss) from continuing operations		2,410	2,343	8,209	7,857
Identifiable assets		1,258,000		1,258,000		1,257,000
Provisions for credit losses and for benefits and claims		309	(21)	288	(106)
Operating Segments | Corporate/Other
Segment reporting information
Revenues, net of interest expense		218	82	800	394
Provision for income taxes		(314)	(103)	(871)	(57)
Income (loss) from continuing operations		183	(1,537)	394	(2,309)
Identifiable assets		52,000		52,000		50,000
Operating Segments | Citi Holdings
Segment reporting information
Revenues, net of interest expense		1,417	2,070	4,924	6,045
Provision for income taxes		90	74	403	10
Income (loss) from continuing operations		31	216	341	(3,558)
Identifiable assets		110,000		110,000		$ 129,000
Provisions for credit losses and for benefits and claims		$ 200	$ 400	$ 800	$ 1,200

[1] Certain prior-period revenue and expense lines and totals were reclassified to conform to the current period’s presentation. See Note 3 to the Consolidated Financial Statements.