EARNINGS PER SHARE (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	3 Months Ended								12 Months Ended
	Dec. 17, 2012	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, 2013		Dec. 31, 2012		Dec. 31, 2011
EARNINGS PER SHARE
Income from continuing operations before attribution of noncontrolling interests		$ 2,325	$ 3,186	$ 4,188	$ 3,931	$ 1,309	$ 485	$ 2,979	$ 3,045	$ 13,630		$ 7,818		$ 11,147
Less: Noncontrolling interests from continuing operations										227		219		148
Net income from continuing operations (for EPS purposes)										13,403		7,599		10,999
Income (loss) from discontinued operations, net of taxes		181	92	30	(33)	(85)	8	7	12	270		(58)		68
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
Less: Preferred dividends										194		26		26
Net income available to common shareholders										13,479		7,515		11,041
Less: Dividends and undistributed earnings allocated to employee restricted and deferred shares that contain nonforfeitable rights to dividends, applicable to basic EPS										263		166		186
Net income allocated to common shareholders for basic										13,216		7,349		10,855
Add: Interest expense, net of tax, and dividends on convertible securities and adjustment of undistributed earnings allocated to employee restricted and deferred shares with nonforfeitable rights to dividends, applicable to diluted EPS										1		11		17
Net income allocated to common shareholders for diluted EPS										$ 13,217		$ 7,360		$ 10,872
Weighted-average common shares outstanding applicable to basic EPS										3,035,800,000		2,930,600,000		2,909,800,000
Reverse stock split conversion ratio										0.10
Effect of dilutive securities
T-DECs (in shares)												84,200,000		87,600,000
Options (in shares)										5,300,000				800,000
Other employee plans (in shares)										500,000		600,000		500,000
Convertible securities (in shares)												100,000		100,000
Adjusted weighted-average common shares outstanding applicable to diluted EPS										3,041,600,000	[1]	3,015,500,000	[1]	2,998,800,000	[1]
Basic earnings per share
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	[1],[2]	$ 2.53	[1],[2]	$ 3.71	[1],[2]
Discontinued operations (in dollars per share)										$ 0.09	[1],[2]	$ (0.02)	[1],[2]	$ 0.02	[1],[2]
Net income (in dollars per share)		$ 0.77	$ 1.01	$ 1.35	$ 1.23	$ 0.39	$ 0.15	$ 0.98	$ 0.98	$ 4.35	[1],[2]	$ 2.51	[1],[2]	$ 3.73	[1],[2]
Diluted earnings per share
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	[1],[2]	$ 2.46	[1],[2]	$ 3.60	[1],[2]
Discontinued operations (in dollars per share)										$ 0.09	[1],[2]	$ (0.02)	[1],[2]	$ 0.02	[1],[2]
Net income (in dollars per share)		$ 0.77	$ 1.00	$ 1.34	$ 1.23	$ 0.38	$ 0.15	$ 0.95	$ 0.95	$ 4.35	[1],[2]	$ 2.44	[1],[2]	$ 3.63	[1],[2]
Number of shares delivered for the final settlement of the prepaid stock purchase contract	96,337,772
Weighted-average options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of earnings per common share (in shares)										4,800,000		35,800,000		24,100,000
Antidilutive securities exercise price (in dollars per share)		$ 101.11				$ 54.23				$ 101.11		$ 54.23		$ 92.89
Warrants issued to U.S. Treasury as part of TARP and loss-sharing agreement | Warrant with the exercise price of $178.50
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of earnings per common share (in shares)										21,000,000		21,000,000		21,000,000
Antidilutive securities exercise price (in dollars per share)		$ 178.50				$ 178.50				$ 178.50		$ 178.50		$ 178.50
Warrants issued to U.S. Treasury as part of TARP and loss-sharing agreement | Warrant with the exercise price of $106.10
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of earnings per common share (in shares)										25,500,000		25,500,000		25,500,000
Antidilutive securities exercise price (in dollars per share)		$ 106.10				$ 106.10				$ 106.10		$ 106.10		$ 106.10

[1] 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.

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