BUSINESS SEGMENTS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015 market		Mar. 31, 2014		Dec. 31, 2014
Segment reporting information
Number of markets	11
Revenues, net of interest expense	$ 19,736	[1]	$ 20,206	[1]
Provision for income taxes	2,120		2,131
Income (loss) from continuing operations	4,817		3,952
Identifiable assets	1,831,801				1,842,181
Provisions for credit losses and for benefits and claims	1,915		1,974
Citicorp | North America
Segment reporting information
Revenues, net of interest expense	8,300		8,300
Citicorp | EMEA
Segment reporting information
Revenues, net of interest expense	3,000		3,100
Citicorp | Latin America
Segment reporting information
Revenues, net of interest expense	2,900		3,200
Citicorp | Asia
Segment reporting information
Revenues, net of interest expense	3,500		3,400
Global Consumer Banking
Segment reporting information
Regional business	4
Provisions for credit losses and for benefits and claims	1,500		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
Provisions for credit losses and for benefits and claims	74		27
Citi Holdings
Segment reporting information
Provisions for credit losses and for benefits and claims	400		400
Operating Segments | Total Citicorp and Corporate/Other
Segment reporting information
Revenues, net of interest expense	17,902		18,221
Provision for income taxes	1,966		2,272
Income (loss) from continuing operations	4,670		4,234
Identifiable assets	1,710,000				1,713,000
Operating Segments | Global Consumer Banking
Segment reporting information
Revenues, net of interest expense	8,662		8,844
Provision for income taxes	920		742
Income (loss) from continuing operations	1,725		1,674
Identifiable assets	387,000				406,000
Operating Segments | Institutional Clients Group
Segment reporting information
Revenues, net of interest expense	9,028		9,154
Provision for income taxes	1,358		1,321
Income (loss) from continuing operations	2,964		2,948
Identifiable assets	1,271,000				1,257,000
Operating Segments | Corporate/Other
Segment reporting information
Revenues, net of interest expense	212		223
Provision for income taxes	(312)		209
Income (loss) from continuing operations	(19)		(388)
Identifiable assets	52,000				50,000
Operating Segments | Citi Holdings
Segment reporting information
Revenues, net of interest expense	1,834		1,985
Provision for income taxes	154		(141)
Income (loss) from continuing operations	147		(282)
Identifiable assets	$ 122,000				$ 129,000

[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.