CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Change in accumulated other comprehensive income (loss), pretax
Balance at the beginning of the period, pretax	$ (27,297)		$ (25,201)		$ (27,596)		$ (25,334)
Change in net unrealized gains (losses) on investment securities, pretax	1,585		(3,235)		2,288		(2,993)
Cash flow hedges, pretax	205		804		386		1,005
Benefit plans, pretax	(239)		649		(294)		997
Foreign currency translation adjustment, pretax	101		(1,863)		(429)		(2,521)
Change, pretax	1,652		(3,645)		1,951		(3,512)
Balance at the end of the period, pretax	(25,645)		(28,846)		(25,645)		(28,846)
Change in accumulated other comprehensive income (loss), tax effect
Balance at the beginning of the period, tax effect	8,151		8,142		8,463		8,438
Change in net unrealized gains (losses) on investment securities, tax effect	(579)		1,192		(854)		1,095
Cash flow hedges, tax effect	(85)		(307)		(148)		(383)
Benefit plans, tax effect	95		(248)		117		(342)
Foreign currency translation adjustment, tax effect	(84)		143		(80)		114
Change, tax effect	(653)		780		(965)		484
Balance at the end of the period, tax effect	7,498		8,922		7,498		8,922
Change in accumulated other comprehensive income (loss), after-tax
Beginning-of-period balance, net of tax	(19,146)		(17,059)		(19,133)		(16,896)
Change in net unrealized gains (losses) on investment securities, after-tax	1,006		(2,043)		1,434		(1,898)
Cash flow hedges, after-tax	120		497		238		622
Benefit plans, after-tax	(144)	[1]	401	[1]	(177)	[1]	655	[1]
Foreign currency translation adjustment, after-tax	17		(1,720)		(509)		(2,407)
Citigroup’s total other comprehensive income (loss)	999		(2,865)		986		(3,028)
End-of-period balance, net of tax	$ (18,147)		$ (19,924)		$ (18,147)		$ (19,924)

[1] Primarily reflects adjustments based on the quarterly actuarial valuations of the Company’s significant pension and postretirement plans and amortization of amounts previously recognized in Other comprehensive income.