CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) (USD $) In Millions, unless otherwise specified							3 Months Ended		9 Months Ended		3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended				3 Months Ended		9 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Sep. 30, 2014 Net unrealized gains (losses) on investment securities	Sep. 30, 2013 Net unrealized gains (losses) on investment securities	Sep. 30, 2014 Net unrealized gains (losses) on investment securities	Sep. 30, 2013 Net unrealized gains (losses) on investment securities	Sep. 30, 2014 Cash flow hedges		Sep. 30, 2013 Cash flow hedges		Sep. 30, 2014 Cash flow hedges		Sep. 30, 2013 Cash flow hedges		Sep. 30, 2014 Benefit plans		Sep. 30, 2013 Benefit plans		Sep. 30, 2014 Benefit plans		Sep. 30, 2013 Benefit plans		Sep. 30, 2014 Foreign currency translation adjustment		Sep. 30, 2013 Foreign currency translation adjustment		Sep. 30, 2014 Foreign currency translation adjustment		Sep. 30, 2013 Foreign currency translation adjustment		Sep. 30, 2014 Accumulated other comprehensive income (loss)	Sep. 30, 2013 Accumulated other comprehensive income (loss)	Sep. 30, 2014 Accumulated other comprehensive income (loss)	Sep. 30, 2013 Accumulated other comprehensive income (loss)
Change in accumulated other comprehensive income (loss)
Beginning-of-period balance, net of tax	$ (19,976)	$ (18,147)	$ (19,133)	$ (18,798)	$ (19,924)	$ (16,896)	$ (206)	$ (1,301)	$ (1,640)	$ 597	$ (1,007)	[1]	$ (1,671)	[1]	$ (1,245)	[1]	$ (2,293)	[1]	$ (4,166)	[2]	$ (4,615)	[2]	$ (3,989)	[2]	$ (5,270)	[2]	$ (12,768)	[3],[4]	$ (12,337)	[3],[4]	$ (12,259)	[3],[4]	$ (9,930)	[3],[4]	$ (18,147)	$ (19,924)	$ (19,133)	$ (16,896)
Other comprehensive income (losses) before reclassifications							(173)	7	1,242	(1,582)	(42)	[1]	177	[1]	62	[1]	509	[1]	17	[2]	261	[2]	(240)	[2]	836	[2]	(1,721)	[3],[4]	506	[3],[4]	(2,230)	[3],[4]	(1,901)	[3],[4]	(1,919)	951	(1,166)	(2,138)
Increase (decrease) due to amounts reclassified from AOCI							(34)	(15)	(15)	(324)	70	[1]	153	[1]	204	[1]	443	[1]	54	[2]	37	[2]	134	[2]	117	[2]									90	175	323	236
Change, net of taxes							(207)	(8)	1,227	(1,906)	28	[1]	330	[1]	266	[1]	952	[1]	71	[2]	298	[2]	(106)	[2]	953	[2]	(1,721)	[3],[4]	506	[3],[4]	(2,230)	[3],[4]	(1,901)	[3],[4]	(1,829)	1,126	(843)	(1,902)
End-of-period balance, net of tax	$ (19,976)	$ (18,147)	$ (19,133)	$ (18,798)	$ (19,924)	$ (16,896)	$ (413)	$ (1,309)	$ (413)	$ (1,309)	$ (979)	[1]	$ (1,341)	[1]	$ (979)	[1]	$ (1,341)	[1]	$ (4,095)	[2]	$ (4,317)	[2]	$ (4,095)	[2]	$ (4,317)	[2]	$ (14,489)	[3],[4]	$ (11,831)	[3],[4]	$ (14,489)	[3],[4]	$ (11,831)	[3],[4]	$ (19,976)	$ (18,798)	$ (19,976)	$ (18,798)

[1] Primarily driven by Citigroup’s pay fixed/receive floating interest rate swap programs that hedge the floating rates on liabilities.

[2] 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.

[3] Primarily reflects the movements in (by order of impact) the Mexican peso, Euro, British pound, and Australian dollar against the U.S. dollar, and changes in related tax effects and hedges for the quarter ended September 30, 2014. Primarily reflects the movements in (by order of impact) the Korean won, British pound, Euro, and Mexican peso against the U.S. dollar, and changes in related tax effects and hedges for the quarter ended June 30, 2014. Primarily reflects the movements in the Russian ruble, Argentine peso, Korean won, and Japanese yen against the U.S. dollar, and changes in related tax effects and hedges for the quarter ended March 31, 2014. Primarily reflects the movements in (by order of impact) the Korean won, Euro, British pound, Mexican peso and Polish zloty against the U.S. dollar, and changes in related tax effects and hedges for the quarter ended September 30, 2013. Primarily reflects the movements in (by order of impact) the Mexican peso, Australian dollar, Indian rupee, and Brazilian real against the U.S. dollar, and changes in related tax effects and hedges for the quarter ended June 30, 2013. primarily reflects the movements in (by order of impact) the Mexican peso, Japanese yen, British pound, and Korean won against the U.S. dollar, and changes in related tax effects and hedges for the quarter ended March 31, 2013.

[4] Reclassified to reflect the allocation of foreign currency translation between net unrealized gains (losses) on investment securities to CTA.