SECURITIZATIONS AND VARIABLE INTEREST ENTITIES (Details 3) (USD $)									3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2013 Consolidated VIEs	Dec. 31, 2012 Consolidated VIEs	Mar. 31, 2013 Significant unconsolidated VIE assets	Dec. 31, 2012 Significant unconsolidated VIE assets	Mar. 31, 2013 Citicorp Credit card securitizations	Mar. 31, 2013 Citicorp Citibank Credit Card Master Trust (Master Trust) Credit card securitizations	Mar. 31, 2013 Citicorp Citibank OMNI Master Trust (Omni Trust) Credit card securitizations	Mar. 31, 2013 Citicorp Consolidated VIEs	Dec. 31, 2012 Citicorp Consolidated VIEs	Mar. 31, 2013 Citicorp Significant unconsolidated VIE assets	Dec. 31, 2012 Citicorp Significant unconsolidated VIE assets	Mar. 31, 2013 Citi Holdings	Dec. 31, 2012 Citi Holdings	Mar. 31, 2013 Citi Holdings Consolidated VIEs	Dec. 31, 2012 Citi Holdings Consolidated VIEs	Mar. 31, 2013 Citi Holdings Significant unconsolidated VIE assets	Dec. 31, 2012 Citi Holdings Significant unconsolidated VIE assets
Variable Interest Entity
Cash and due from banks (including segregated cash and other deposits)	$ 31,150,000,000	$ 36,453,000,000	$ 26,505,000,000	$ 28,701,000,000	$ 723,000,000	$ 498,000,000						$ 300,000,000	$ 300,000,000					$ 500,000,000	$ 200,000,000
Trading account assets	308,321,000,000	320,929,000,000			1,915,000,000	481,000,000	4,300,000,000	4,500,000,000				1,900,000,000	500,000,000	3,800,000,000	4,000,000,000					500,000,000	500,000,000
Investments	304,859,000,000	312,326,000,000			11,551,000,000	10,751,000,000	5,600,000,000	6,100,000,000				11,500,000,000	10,700,000,000	4,900,000,000	5,400,000,000					700,000,000	700,000,000
Total loans, net	622,637,000,000	630,009,000,000			78,317,000,000	111,766,000,000	16,000,000,000	15,500,000,000				68,300,000,000	100,800,000,000	15,300,000,000	14,600,000,000			10,000,000,000	11,000,000,000	700,000,000	900,000,000
Other assets	142,736,000,000	145,660,000,000			1,267,000,000	674,000,000	2,200,000,000	1,900,000,000				1,100,000,000	500,000,000	1,600,000,000	1,400,000,000			200,000,000	200,000,000	600,000,000	500,000,000
Total assets	1,881,734,000,000	1,864,660,000,000			93,773,000,000	124,170,000,000	28,100,000,000	28,000,000,000				83,100,000,000	112,800,000,000	25,600,000,000	25,400,000,000	149,000,000,000	156,000,000,000	10,700,000,000	11,400,000,000	2,500,000,000	2,600,000,000
Short-term borrowings					18,100,000,000	17,900,000,000						18,100,000,000	17,900,000,000
Long-term debt	234,326,000,000	239,463,000,000			25,593,000,000	26,346,000,000
Long-term debt					25,600,000,000	26,400,000,000						23,100,000,000	23,800,000,000					2,500,000,000	2,600,000,000
Other liabilities					2,200,000,000	1,200,000,000						2,100,000,000	1,100,000,000					100,000,000	100,000,000
Total Liabilities					45,900,000,000	45,500,000,000						43,300,000,000	42,800,000,000					2,600,000,000	2,700,000,000
Amount removed from receivables									$ 27,000,000,000	$ 12,000,000,000	$ 15,000,000,000