SECURITIZATIONS AND VARIABLE INTEREST ENTITIES (Details 6) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Y	Jun. 30, 2011
U.S. government-sponsored agency guaranteed | Citicorp
Cash Flows Between Transferor and Transferee
Proceeds from new securitizations	$ 10,300,000,000		$ 26,900,000,000
Contractual servicing fees received	100,000,000		200,000,000
Gains (losses) recognized on the securitization	3,000,000		5,900,000
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Weighted average discount rate, date of sale or securitization (as a percent)	11.50%		11.20%
Weighted average constant prepayment rate, date of sale or securitization (as a percent)	9.10%		10.00%
Key assumptions used in measuring fair value related to transferor's continuing involvement
Weighted average discount rate, transferor's continuing involvement (as a percent)			6.40%
Weighted average constant prepayment rate, transferor's continuing involvement (as a percent)			23.30%
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests	2,419,000,000		2,419,000,000
Carrying value of retained interests, impact of 10% adverse change in discount rate	(60,000,000)		(60,000,000)
Carrying value of retained interests, impact of 20% adverse change in discount rate	(116,000,000)		(116,000,000)
Carrying value of retained interests, impact of 10% adverse change in constant prepayment rate	(107,000,000)		(107,000,000)
Carrying value of retained interests, impact of 20% adverse change in constant prepayment rate	(215,000,000)		(215,000,000)
Carrying value of retained interests, impact of 10% adverse change in anticipated net credit losses	(14,000,000)		(14,000,000)
Carrying value of retained interests, impact of 20% adverse change in anticipated net credit losses	(27,000,000)		(27,000,000)
U.S. government-sponsored agency guaranteed | Citicorp | Low end of range
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)	1.50%		1.50%
Constant prepayment rate, date of sale or securitization (as a percent)	8.10%		7.30%
Key assumptions used in measuring fair value related to transferor's continuing involvement
Discount rate, transferor's continuing involvement (as a percent)			1.10%
Constant prepayment rate, transferor's continuing involvement (as a percent)			9.70%
U.S. government-sponsored agency guaranteed | Citicorp | High end of range
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)	14.40%		14.40%
Constant prepayment rate, date of sale or securitization (as a percent)	21.40%		21.40%
Key assumptions used in measuring fair value related to transferor's continuing involvement
Discount rate, transferor's continuing involvement (as a percent)			13.60%
Constant prepayment rate, transferor's continuing involvement (as a percent)			26.90%
U.S. government-sponsored agency guaranteed | Citi Holdings
Cash Flows Between Transferor and Transferee
Proceeds from new securitizations	100,000,000		300,000,000
Contractual servicing fees received	100,000,000		200,000,000
Gains (losses) recognized on the securitization	10,600,000	9,000,000	30,800,000	27,000,000
Key assumptions used in measuring fair value related to transferor's continuing involvement
Discount rate, transferor's continuing involvement (as a percent)			8.10%
Weighted average discount rate, transferor's continuing involvement (as a percent)			8.10%
Constant prepayment rate, transferor's continuing involvement (as a percent)			26.90%
Weighted average constant prepayment rate, transferor's continuing involvement (as a percent)			26.90%
Weighted average life, transferor's continuing involvement (in years)			4.0
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests	691,000,000		691,000,000
Carrying value of retained interests, impact of 10% adverse change in discount rate	(22,000,000)		(22,000,000)
Carrying value of retained interests, impact of 20% adverse change in discount rate	(42,000,000)		(42,000,000)
Carrying value of retained interests, impact of 10% adverse change in constant prepayment rate	(58,000,000)		(58,000,000)
Carrying value of retained interests, impact of 20% adverse change in constant prepayment rate	(112,000,000)		(112,000,000)
Carrying value of retained interests, impact of 10% adverse change in anticipated net credit losses	(44,000,000)		(44,000,000)
Carrying value of retained interests, impact of 20% adverse change in anticipated net credit losses	(87,000,000)		(87,000,000)
Non-agency-sponsored mortgages | Citicorp
Cash Flows Between Transferor and Transferee
Proceeds from new securitizations	200,000,000		500,000,000
Gains (losses) recognized on the securitization	(1,000,000)		(1,500,000)
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Anticipated net credit losses, date of sale or securitization (as a percent)		72.00%
Senior interests | Citicorp
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)	13.40%		13.40%
Weighted average discount rate, date of sale or securitization (as a percent)	13.40%		13.40%
Constant prepayment rate, date of sale or securitization (as a percent)	8.10%		8.10%
Weighted average constant prepayment rate, date of sale or securitization (as a percent)	8.10%		8.10%
Anticipated net credit losses, date of sale or securitization (as a percent)	50.50%		50.50%
Weighted average anticipated net credit losses, date of sale or securitization (as a percent)	50.50%		50.50%
Key assumptions used in measuring fair value related to transferor's continuing involvement
Weighted average discount rate, transferor's continuing involvement (as a percent)			21.10%
Weighted average constant prepayment rate, transferor's continuing involvement (as a percent)			14.00%
Weighted average anticipated credit losses, transferor's continuing involvement (as a percent)			38.90%
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests	76,000,000		76,000,000
Carrying value of retained interests, impact of 10% adverse change in discount rate	(3,000,000)		(3,000,000)
Carrying value of retained interests, impact of 20% adverse change in discount rate	(6,000,000)		(6,000,000)
Carrying value of retained interests, impact of 10% adverse change in constant prepayment rate	(2,000,000)		(2,000,000)
Carrying value of retained interests, impact of 20% adverse change in constant prepayment rate	(4,000,000)		(4,000,000)
Carrying value of retained interests, impact of 10% adverse change in anticipated net credit losses	(1,000,000)		(1,000,000)
Carrying value of retained interests, impact of 20% adverse change in anticipated net credit losses	(3,000,000)		(3,000,000)
Senior interests | Citicorp | Low end of range
Key assumptions used in measuring fair value related to transferor's continuing involvement
Discount rate, transferor's continuing involvement (as a percent)			1.80%
Constant prepayment rate, transferor's continuing involvement (as a percent)			2.20%
Anticipated credit losses, transferor's continuing involvement (as a percent)			0.00%
Senior interests | Citicorp | High end of range
Key assumptions used in measuring fair value related to transferor's continuing involvement
Discount rate, transferor's continuing involvement (as a percent)			55.70%
Constant prepayment rate, transferor's continuing involvement (as a percent)			31.10%
Anticipated credit losses, transferor's continuing involvement (as a percent)			75.20%
Senior interests | Citi Holdings
Key assumptions used in measuring fair value related to transferor's continuing involvement
Weighted average discount rate, transferor's continuing involvement (as a percent)			8.90%
Constant prepayment rate, transferor's continuing involvement (as a percent)			23.30%
Weighted average constant prepayment rate, transferor's continuing involvement (as a percent)			23.30%
Anticipated credit losses, transferor's continuing involvement (as a percent)			0.30%
Weighted average anticipated credit losses, transferor's continuing involvement (as a percent)			0.30%
Weighted average life, transferor's continuing involvement (in years)			4.3
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests	113,000,000		113,000,000
Carrying value of retained interests, impact of 10% adverse change in discount rate	(3,000,000)		(3,000,000)
Carrying value of retained interests, impact of 20% adverse change in discount rate	(6,000,000)		(6,000,000)
Carrying value of retained interests, impact of 10% adverse change in constant prepayment rate	(7,000,000)		(7,000,000)
Carrying value of retained interests, impact of 20% adverse change in constant prepayment rate	(13,000,000)		(13,000,000)
Carrying value of retained interests, impact of 10% adverse change in anticipated net credit losses	(7,000,000)		(7,000,000)
Carrying value of retained interests, impact of 20% adverse change in anticipated net credit losses	(15,000,000)		(15,000,000)
Senior interests | Citi Holdings | Low end of range
Key assumptions used in measuring fair value related to transferor's continuing involvement
Discount rate, transferor's continuing involvement (as a percent)			8.90%
Senior interests | Citi Holdings | High end of range
Key assumptions used in measuring fair value related to transferor's continuing involvement
Discount rate, transferor's continuing involvement (as a percent)			10.00%
Subordinated interests | Citicorp
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Weighted average discount rate, date of sale or securitization (as a percent)	13.90%		17.10%
Weighted average constant prepayment rate, date of sale or securitization (as a percent)	4.90%		3.80%
Weighted average anticipated net credit losses, date of sale or securitization (as a percent)	58.50%		59.00%
Key assumptions used in measuring fair value related to transferor's continuing involvement
Weighted average discount rate, transferor's continuing involvement (as a percent)			16.40%
Weighted average constant prepayment rate, transferor's continuing involvement (as a percent)			8.50%
Weighted average anticipated credit losses, transferor's continuing involvement (as a percent)			55.20%
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests	460,000,000		460,000,000
Carrying value of retained interests, impact of 10% adverse change in discount rate	(31,000,000)		(31,000,000)
Carrying value of retained interests, impact of 20% adverse change in discount rate	(58,000,000)		(58,000,000)
Carrying value of retained interests, impact of 10% adverse change in constant prepayment rate	(11,000,000)		(11,000,000)
Carrying value of retained interests, impact of 20% adverse change in constant prepayment rate	(22,000,000)		(22,000,000)
Carrying value of retained interests, impact of 10% adverse change in anticipated net credit losses	(9,000,000)		(9,000,000)
Carrying value of retained interests, impact of 20% adverse change in anticipated net credit losses	(18,000,000)		(18,000,000)
Subordinated interests | Citicorp | Low end of range
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)	10.70%		10.70%
Constant prepayment rate, date of sale or securitization (as a percent)	4.80%		2.20%
Anticipated net credit losses, date of sale or securitization (as a percent)	57.70%		55.20%
Key assumptions used in measuring fair value related to transferor's continuing involvement
Discount rate, transferor's continuing involvement (as a percent)			4.80%
Constant prepayment rate, transferor's continuing involvement (as a percent)			0.30%
Anticipated credit losses, transferor's continuing involvement (as a percent)			28.50%
Subordinated interests | Citicorp | High end of range
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)	15.80%		19.30%
Constant prepayment rate, date of sale or securitization (as a percent)	5.10%		5.40%
Anticipated net credit losses, date of sale or securitization (as a percent)	59.80%		62.90%
Key assumptions used in measuring fair value related to transferor's continuing involvement
Discount rate, transferor's continuing involvement (as a percent)			71.60%
Constant prepayment rate, transferor's continuing involvement (as a percent)			26.50%
Anticipated credit losses, transferor's continuing involvement (as a percent)			90.00%
Subordinated interests | Citi Holdings
Key assumptions used in measuring fair value related to transferor's continuing involvement
Discount rate, transferor's continuing involvement (as a percent)			6.60%
Weighted average discount rate, transferor's continuing involvement (as a percent)			6.60%
Constant prepayment rate, transferor's continuing involvement (as a percent)			7.60%
Weighted average constant prepayment rate, transferor's continuing involvement (as a percent)			7.60%
Anticipated credit losses, transferor's continuing involvement (as a percent)			58.90%
Weighted average anticipated credit losses, transferor's continuing involvement (as a percent)			58.90%
Weighted average life, transferor's continuing involvement (in years)			9.1
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests	20,000,000		20,000,000
Carrying value of retained interests, impact of 10% adverse change in discount rate	(1,000,000)		(1,000,000)
Carrying value of retained interests, impact of 20% adverse change in discount rate	(1,000,000)		(1,000,000)
Carrying value of retained interests, impact of 20% adverse change in constant prepayment rate	(1,000,000)		(1,000,000)
Carrying value of retained interests, impact of 10% adverse change in anticipated net credit losses	(1,000,000)		(1,000,000)
Carrying value of retained interests, impact of 20% adverse change in anticipated net credit losses	(2,000,000)		(2,000,000)
Mortgage-backed securities | Citicorp
Cash Flows Between Transferor and Transferee
Proceeds from new securitizations		11,100,000,000		25,900,000,000
Contractual servicing fees received		100,000,000		300,000,000
Gains (losses) recognized on the securitization		(6,400,000)		(7,700,000)
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Anticipated net credit losses, date of sale or securitization (as a percent)		72.00%
Mortgage-backed securities | Citicorp | Low end of range
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)		0.60%		0.60%
Constant prepayment rate, date of sale or securitization (as a percent)		1.00%		1.00%
Anticipated net credit losses, date of sale or securitization (as a percent)				11.40%
Mortgage-backed securities | Citicorp | High end of range
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)		23.70%		28.30%
Constant prepayment rate, date of sale or securitization (as a percent)		22.60%		22.60%
Anticipated net credit losses, date of sale or securitization (as a percent)				72.00%
Mortgage-backed securities | Citi Holdings
Cash Flows Between Transferor and Transferee
Proceeds from new securitizations		300,000,000		600,000,000
Contractual servicing fees received		100,000,000		400,000,000
Collateralized debt obligations (CDOs) | Citi Holdings
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests	14,000,000		14,000,000
Carrying value of retained interests, impact of 10% adverse change in discount rate	(2,000,000)		(2,000,000)
Carrying value of retained interests, impact of 20% adverse change in discount rate	(3,000,000)		(3,000,000)
Collateralized debt obligations (CDOs) | Citi Holdings | Low end of range
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)			46.90%
Collateralized debt obligations (CDOs) | Citi Holdings | High end of range
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)			51.60%
Collateralized loan obligations (CLOs) | Citi Holdings
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests	398,000,000		398,000,000
Carrying value of retained interests, impact of 10% adverse change in discount rate	(6,000,000)		(6,000,000)
Carrying value of retained interests, impact of 20% adverse change in discount rate	(13,000,000)		(13,000,000)
Collateralized loan obligations (CLOs) | Citi Holdings | Low end of range
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)			3.20%
Collateralized loan obligations (CLOs) | Citi Holdings | High end of range
Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables
Discount rate, date of sale or securitization (as a percent)			3.50%
Asset-based financing | Citi Holdings
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests	2,745,000,000		2,745,000,000
Credit card securitizations | Citicorp
Cash Flows Between Transferor and Transferee
Pay down of maturing notes	(6,400,000,000)	(10,800,000,000)	(11,400,000,000)	(10,800,000,000)
Credit card securitizations | Citi Holdings
Cash Flows Between Transferor and Transferee
Proceeds from new securitizations		3,000,000,000		3,900,000,000
Pay down of maturing notes	$ (100,000,000)	$ (4,800,000,000)	$ (100,000,000)	$ (7,200,000,000)