DEBT (Details 3) (USD $)		0 Months Ended								9 Months Ended				0 Months Ended
	Sep. 30, 2013	Sep. 13, 2013 Subordinated notes item	Sep. 30, 2013 Citigroup Capital III	Sep. 30, 2013 Citigroup Capital IX	Sep. 30, 2013 Citigroup Capital X	Sep. 30, 2013 Citigroup Capital XI	Sep. 30, 2013 Citigroup Capital XIII	Sep. 30, 2013 Citigroup Capital XVII	Sep. 30, 2013 Citigroup Capital XVIII	Sep. 30, 2013 Adam Capital Trust III	Sep. 30, 2013 Adam Statutory Trust III	Sep. 30, 2013 Adam Statutory Trust IV	Sep. 30, 2013 Adam Statutory Trust V	Sep. 13, 2013 Citigroup Capital XXXIII
Trust Preferred Securities
Amount exchanged into subordinated debt														$ 2,225,000,000
Number of debt issues		2
Securities issued (in shares)			194,053	33,874,813	14,757,823	18,387,128	89,840,000	28,047,927	99,901	17,500	25,000	40,000	35,000
Liquidation value	5,097,000,000		194,000,000	847,000,000	369,000,000	460,000,000	2,246,000,000	701,000,000	162,000,000	18,000,000	25,000,000	40,000,000	35,000,000
Coupon rate (as a percent)			7.625%	6.00%	6.10%	6.00%	7.875%	6.35%	6.829%
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	1,047,675	456,428	568,675	1,000	20,000	50	542	774	1,238	1,083
Debt issued		2,420,000,000
Number of tranches		2
Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance	$ 5,158,000,000		$ 200,000,000	$ 873,000,000	$ 380,000,000	$ 474,000,000	$ 2,246,000,000	$ 702,000,000	$ 162,000,000	$ 18,000,000	$ 26,000,000	$ 41,000,000	$ 36,000,000