DEBT (Details 3) (USD $)														0 Months Ended		0 Months Ended	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2013 Citigroup Capital III	Mar. 31, 2013 Citigroup Capital VII	Mar. 31, 2013 Citigroup Capital VIII	Mar. 31, 2013 Citigroup Capital IX	Mar. 31, 2013 Citigroup Capital X	Mar. 31, 2013 Citigroup Capital XI	Mar. 31, 2013 Citigroup Capital XIII	Mar. 31, 2013 Citigroup Capital XIV	Mar. 31, 2013 Citigroup Capital XV	Mar. 31, 2013 Citigroup Capital XVI	Mar. 31, 2013 Citigroup Capital XVII	Mar. 31, 2013 Citigroup Capital XVIII	Feb. 04, 2013 Citigroup Capital XXXIII	Mar. 31, 2013 Citigroup Capital XXXIII	Feb. 04, 2013 Citigroup Capital XXXIII Subordinated notes	Mar. 31, 2013 Adam Capital Trust III	Mar. 31, 2013 Adam Statutory Trust III	Mar. 31, 2013 Adam Statutory Trust IV	Mar. 31, 2013 Adam Statutory Trust V
Trust Preferred Securities
Amount exchanged into subordinated debt														$ 800,000,000
Debt issued																894,000,000
Trust preferred securities outstanding														3,025,000,000	2,225,000,000
Gain (loss) on amount exchanged														0
Discount on the newly issued debt																94,000,000
Securities issued (in shares)		194,053	35,885,898	43,651,597	33,874,813	14,757,823	18,387,128	89,840,000	12,227,281	25,210,733	38,148,947	28,047,927	99,901		3,025,000		17,500	25,000	40,000	35,000
Liquidation value	11,190,000,000	194,000,000	897,000,000	1,091,000,000	847,000,000	369,000,000	460,000,000	2,246,000,000	306,000,000	630,000,000	954,000,000	701,000,000	152,000,000		2,225,000,000		18,000,000	25,000,000	40,000,000	35,000,000
Coupon rate (as a percent)		7.625%	7.125%	6.95%	6.00%	6.10%	6.00%	7.875%	6.875%	6.50%	6.45%	6.35%	6.829%		8.00%
Description of coupon rate basis																	three months LIBOR	three months LIBOR	three months LIBOR	three months LIBOR
Coupon rate, basis spread (as a percent)																	3.35%	3.25%	2.95%	2.79%
Common shares issued to parent		6,003	1,109,874	1,350,050	1,047,675	456,428	568,675	1,000	40,000	40,000	20,000	20,000	50		100		542	774	1,238	1,083
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	$ 11,315,000,000	$ 200,000,000	$ 925,000,000	$ 1,125,000,000	$ 873,000,000	$ 380,000,000	$ 474,000,000	$ 2,246,000,000	$ 307,000,000	$ 631,000,000	$ 954,000,000	$ 702,000,000	$ 152,000,000		$ 2,225,000,000		$ 18,000,000	$ 26,000,000	$ 41,000,000	$ 36,000,000