SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended											12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)
Revenues, net of interest expense	$ 17,780	$ 17,880	$ 20,479	$ 20,227	$ 17,917	$ 13,703	$ 18,387	$ 19,121				$ 76,366		$ 69,128		$ 77,331
Operating expenses	12,293	11,655	12,140	12,267	13,709	12,092	11,994	12,179				48,355	[1]	49,974	[1]	50,250	[1]
Provisions for credit losses and for benefits and claims	2,072	1,959	2,024	2,459	3,113	2,620	2,696	2,900				8,514		11,329		12,359
Income (loss) from continuing operations before income taxes	3,415	4,266	6,315	5,501	1,095	(1,009)	3,697	4,042				19,497		7,825		14,722
Income taxes (benefits)	1,090	1,080	2,127	1,570	(214)	(1,494)	718	997				5,867		7		3,575
Income from continuing operations	2,325	3,186	4,188	3,931	1,309	485	2,979	3,045				13,630		7,818		11,147
Income (loss) from discontinued operations, net of taxes	181	92	30	(33)	(85)	8	7	12				270		(58)		68
Net income before attribution of noncontrolling interests	2,506	3,278	4,218	3,898	1,224	493	2,986	3,057				13,900		7,760		11,215
Noncontrolling interests	50	51	36	90	28	25	40	126				227		219		148
Citigroup's net income	$ 2,456	$ 3,227	$ 4,182	$ 3,808	$ 1,196	$ 468	$ 2,946	$ 2,931				$ 13,673		$ 7,541		$ 11,067
Earnings per share Basic
Income from continuing operations (in dollars per share)	$ 0.71	$ 0.98	$ 1.34	$ 1.24	$ 0.42	$ 0.15	$ 0.98	$ 0.98				$ 4.27	[2],[3]	$ 2.53	[2],[3]	$ 3.71	[2],[3]
Net income (in dollars per share)	$ 0.77	$ 1.01	$ 1.35	$ 1.23	$ 0.39	$ 0.15	$ 0.98	$ 0.98				$ 4.35	[2],[3]	$ 2.51	[2],[3]	$ 3.73	[2],[3]
Earnings per share Diluted
Income from continuing operations (in dollars per share)	$ 0.71	$ 0.98	$ 1.33	$ 1.24	$ 0.41	$ 0.15	$ 0.95	$ 0.95				$ 4.26	[2],[3]	$ 2.46	[2],[3]	$ 3.60	[2],[3]
Net income (in dollars per share)	$ 0.77	$ 1.00	$ 1.34	$ 1.23	$ 0.38	$ 0.15	$ 0.95	$ 0.95				$ 4.35	[2],[3]	$ 2.44	[2],[3]	$ 3.63	[2],[3]
Common stock price per share
High (in dollars per share)	$ 53.29	$ 53.00	$ 53.27	$ 47.60	$ 40.17	$ 34.79	$ 36.87	$ 38.08				$ 53.29		$ 40.17
Low (in dollars per share)	$ 47.67	$ 47.67	$ 42.50	$ 41.15	$ 32.75	$ 25.24	$ 24.82	$ 28.17				$ 47.67		$ 32.75
Close (in dollars per share)	$ 52.11	$ 48.51	$ 47.97	$ 44.24	$ 39.56	$ 32.72	$ 27.41	$ 36.55				$ 52.11		$ 39.56
Dividends per share of common stock (in dollars per share)	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01

[1] Citigroup recorded repositioning charges of $590 million for 2013, $1,375 million for 2012 and $706 million for 2011.

[2] All per share amounts and Citigroup shares outstanding for all periods reflect Citigroup's 1-for-10 reverse stock split, which was effective May 6, 2011.

[3] Due to rounding, earnings per share on continuing operations and discontinued operations may not sum to earnings per share on net income.