SECURITIZATIONS AND VARIABLE INTEREST ENTITIES (Details 3) (USD $)	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Variable Interest Entity
Cash and due from banks (including segregated cash and other deposits)	$ 33,802,000,000	$ 28,701,000,000	$ 28,950,000,000	$ 27,972,000,000
Trading account assets	315,201,000,000	291,734,000,000
Investments	295,474,000,000	293,413,000,000
Total loans, net	632,507,000,000	617,127,000,000
Other assets	141,873,000,000	148,911,000,000
Total assets	1,931,346,000,000	1,873,878,000,000
Long-term debt	271,862,000,000	323,505,000,000
Consolidated VIEs
Variable Interest Entity
Cash and due from banks (including segregated cash and other deposits)	589,000,000	536,000,000
Trading account assets	570,000,000	567,000,000
Investments	7,429,000,000	10,582,000,000
Total loans, net	107,249,000,000	119,055,000,000
Other assets	1,252,000,000	859,000,000
Total assets	117,089,000,000	131,599,000,000
Short-term borrowings	18,700,000,000	23,300,000,000
Long-term debt	35,641,000,000	50,451,000,000
Long-term debt	35,700,000,000	50,400,000,000
Other liabilities	600,000,000	600,000,000
Total Liabilities	55,000,000,000	74,300,000,000
Significant unconsolidated VIE assets
Variable Interest Entity
Trading account assets	3,900,000,000	6,500,000,000
Investments	6,100,000,000	8,300,000,000
Total loans, net	14,700,000,000	10,600,000,000
Other assets	1,900,000,000	2,600,000,000
Total assets	26,600,000,000	28,000,000,000
Long-term debt	200,000,000	200,000,000
Long-term debt	200,000,000	200,000,000
Total Liabilities	200,000,000	200,000,000
Total Liabilities	200,000,000	200,000,000
Citicorp
Variable Interest Entity
Total assets	1,458,000,000,000	1,365,000,000,000
Citicorp | Consolidated VIEs
Variable Interest Entity
Cash and due from banks (including segregated cash and other deposits)	200,000,000	200,000,000
Trading account assets	500,000,000	400,000,000
Investments	7,400,000,000	10,600,000,000
Total loans, net	97,700,000,000	109,000,000,000
Other assets	1,000,000,000	500,000,000
Total assets	106,800,000,000	120,700,000,000
Short-term borrowings	18,700,000,000	22,500,000,000
Long-term debt	29,700,000,000	44,800,000,000
Other liabilities	500,000,000	400,000,000
Total Liabilities	48,900,000,000	67,700,000,000
Citicorp | Significant unconsolidated VIE assets
Variable Interest Entity
Trading account assets	3,400,000,000	5,500,000,000
Investments	3,300,000,000	3,900,000,000
Total loans, net	13,700,000,000	9,000,000,000
Other assets	1,400,000,000	1,600,000,000
Total assets	21,800,000,000	20,000,000,000
Long-term debt	200,000,000	200,000,000
Long-term debt	200,000,000	200,000,000
Total Liabilities	200,000,000	200,000,000
Total Liabilities	200,000,000	200,000,000
Citi Holdings
Variable Interest Entity
Total assets	171,000,000,000	225,000,000,000
Citi Holdings | Consolidated VIEs
Variable Interest Entity
Cash and due from banks (including segregated cash and other deposits)	400,000,000	400,000,000
Trading account assets		100,000,000
Total loans, net	9,600,000,000	10,100,000,000
Other assets	200,000,000	300,000,000
Total assets	10,200,000,000	10,900,000,000
Short-term borrowings		800,000,000
Long-term debt	6,000,000,000	5,600,000,000
Other liabilities	100,000,000	200,000,000
Total Liabilities	6,100,000,000	6,600,000,000
Citi Holdings | Significant unconsolidated VIE assets
Variable Interest Entity
Trading account assets	500,000,000	1,000,000,000
Investments	2,800,000,000	4,400,000,000
Total loans, net	1,000,000,000	1,600,000,000
Other assets	500,000,000	1,000,000,000
Total assets	$ 4,800,000,000	$ 8,000,000,000