SECURITIZATIONS AND VARIABLE INTEREST ENTITIES (Details 8) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Variable Interest Entity
Total unconsolidated VIE assets		$ 449,362,000,000		$ 499,481,000,000
Maximum exposure to unconsolidated VIEs		37,458,000,000		45,971,000,000
Citicorp
Variable Interest Entity
Total unconsolidated VIE assets		338,525,000,000		354,493,000,000
Maximum exposure to unconsolidated VIEs		33,958,000,000		41,644,000,000
Citicorp | Asset-based financing
Variable Interest Entity
Total unconsolidated VIE assets		40,000,000,000		40,200,000,000
Maximum exposure to unconsolidated VIEs		17,700,000,000		17,100,000,000
Cash flows received on retained interest and other net cash flows		600,000,000
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests		1,326,000,000		1,726,000,000
Citi Holdings
Variable Interest Entity
Total unconsolidated VIE assets		110,837,000,000		144,988,000,000
Maximum exposure to unconsolidated VIEs		3,500,000,000		4,327,000,000
Citi Holdings | Asset-based financing
Variable Interest Entity
Total unconsolidated VIE assets		3,600,000,000		4,200,000,000
Maximum exposure to unconsolidated VIEs		900,000,000		1,200,000,000
Cash flows received on retained interest and other net cash flows	400,000,000	200,000,000	1,700,000,000
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests		95,000,000		339,000,000
Citi Holdings | Collateralized debt obligations (CDOs)
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests		17,000,000		16,000,000
Citi Holdings | Collateralized loan obligations (CLOs)
Sensitivity analysis of fair value of interests continued to be held by transferor
Carrying value of retained interests		1,373,000,000		428,000,000
Commercial and other real estate | Citicorp | Asset-based financing
Variable Interest Entity
Total unconsolidated VIE assets		14,200,000,000		16,100,000,000
Maximum exposure to unconsolidated VIEs		2,900,000,000		3,100,000,000
Commercial and other real estate | Citi Holdings | Asset-based financing
Variable Interest Entity
Total unconsolidated VIE assets		800,000,000		900,000,000
Maximum exposure to unconsolidated VIEs		300,000,000		300,000,000
Corporate loans | Citicorp | Asset-based financing
Variable Interest Entity
Total unconsolidated VIE assets		2,200,000,000		2,000,000,000
Maximum exposure to unconsolidated VIEs		1,800,000,000		1,600,000,000
Corporate loans | Citi Holdings | Asset-based financing
Variable Interest Entity
Total unconsolidated VIE assets		100,000,000		400,000,000
Maximum exposure to unconsolidated VIEs		100,000,000		300,000,000
Hedge funds and equities | Citicorp | Asset-based financing
Variable Interest Entity
Total unconsolidated VIE assets				600,000,000
Maximum exposure to unconsolidated VIEs				400,000,000
Airplanes, ships and other assets | Citicorp | Asset-based financing
Variable Interest Entity
Total unconsolidated VIE assets		23,600,000,000		21,500,000,000
Maximum exposure to unconsolidated VIEs		13,000,000,000		12,000,000,000
Airplanes, ships and other assets | Citi Holdings | Asset-based financing
Variable Interest Entity
Total unconsolidated VIE assets		2,700,000,000		2,900,000,000
Maximum exposure to unconsolidated VIEs		$ 500,000,000		$ 600,000,000