EARNINGS PER SHARE (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Earnings Per Share [Abstract]
Income from continuing operations before attribution of noncontrolling interests	$ 2,914	[1]	$ 3,186	[1]	$ 7,118	[1]	$ 11,305	[1]
Less: Noncontrolling interests from continuing operations	59		51		154		177
Net income from continuing operations (for EPS purposes)	2,855		3,135		6,964		11,128
Income (loss) from discontinued operations, net of taxes	(16)		92		(1)		89
Citigroup’s net income	2,839		3,227		6,963		11,217
Less: Preferred dividends	128	[2]	110	[2]	352	[2]	123	[2]
Net income available to common shareholders	2,711		3,117		6,611		11,094
Less: Dividends and undistributed earnings allocated to employee restricted and deferred shares with nonforfeitable rights to dividends, applicable to basic EPS	44		61		108		217
Net income allocated to common shareholders for basic EPS	2,667		3,056		6,503		10,877
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	0		0		0		2
Net income allocated to common shareholders for diluted EPS	$ 2,667		$ 3,056		$ 6,503		$ 10,879
Weighted-average common shares outstanding applicable to basic EPS	3,029.5		3,034.3		3,033.5		3,038.4
Effect of dilutive securities
Options (in shares)	5.1	[3]	6.1	[3]	5.0	[3]	5.0	[3]
Other employee plans (in shares)	0.2		0.5		0.3		0.5
Convertible securities (in shares)	0	[4]	0	[4]	0	[4]	0.1	[4]
Adjusted weighted-average common shares outstanding applicable to diluted EPS	3,034.8		3,040.9		3,038.8		3,044.0
Basic earnings per share
Income from continuing operations (in dollars per share)	$ 0.89	[5]	$ 0.98	[5]	$ 2.14	[5]	$ 3.55	[5]
Discontinued operations (in dollars per share)	$ (0.01)	[5]	$ 0.03	[5]	$ 0.00	[5]	$ 0.03	[5]
Net income (in dollars per share)	$ 0.88	[5]	$ 1.01	[5]	$ 2.14	[5]	$ 3.58	[5]
Diluted earnings per share
Income from continuing operations (in dollars per share)	$ 0.88	[5]	$ 0.98	[5]	$ 2.14	[5]	$ 3.55	[5]
Discontinued operations (in dollars per share)	$ (0.01)	[5]	$ 0.03	[5]	$ 0.00	[5]	$ 0.03	[5]
Net income (in dollars per share)	$ 0.88	[5]	$ 1.00	[5]	$ 2.14	[5]	$ 3.57	[5]
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)	1.9		1.5
Antidilutive securities exercise price (in dollars per share)	$ 157.90		$ 214.30		$ 157.90		$ 214.30
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)	21.0
Antidilutive securities exercise price (in dollars per share)	$ 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)			25.5
Antidilutive securities exercise price (in dollars per share)			$ 106.10				$ 106.10

[1] Includes pretax provisions (credits) for credit losses and for benefits and claims in the GCB results of $1.4 billion and $1.7 billion; in the ICG results of $(21) million and $139 million; and in Citi Holdings results of $0.4 billion and $0.1 billion for the three months ended September 30, 2014 and 2013, respectively. Includes pretax provisions (credits) for credit losses and for benefits and claims in the GCB results of $4.5 billion and $5.0 billion; in the ICG results of $(106) million and $174 million; and in Citi Holdings results of $1.0 billion and $1.3 billion for the nine months ended September 30, 2014 and 2013, respectively.

[2] See Note 19 to the Consolidated Financial Statements for the potential future impact of preferred stock dividends.

[3] During the third quarters of 2014 and 2013, weighted-average options to purchase 1.9 million and 1.5 million shares of common stock, respectively, were outstanding but not included in the computation of earnings per share because the weighted-average exercise prices of $157.90 and $214.30, respectively, were anti-dilutive.

[4] Warrants issued to the U.S. Treasury as part of the Troubled Asset Relief Program (TARP) and the loss-sharing agreement (all of which were subsequently sold to the public in January 2011), with an exercise price of $178.50 and $106.10 for approximately 21.0 million and 25.5 million shares of Citigroup common stock, respectively, were not included in the computation of earnings per share in the third quarters of 2014 and 2013 because they were anti-dilutive.

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