SECURITIZATIONS AND VARIABLE INTEREST ENTITIES (Details 4) (USD $)	3 Months Ended			3 Months Ended				3 Months Ended
	Mar. 31, 2013	Mar. 31, 2013 Citicorp	Dec. 31, 2012 Citicorp	Mar. 31, 2013 Citicorp Credit card securitizations	Mar. 31, 2012 Citicorp Credit card securitizations	Mar. 31, 2013 Citi Holdings	Dec. 31, 2012 Citi Holdings	Mar. 31, 2013 Citi Holdings Credit card securitizations
Ownership interests in principal amount of trust credit card receivables
Sold to investors via trust-issued securities		$ 22,100,000,000	$ 22,900,000,000			$ 100,000,000	$ 100,000,000
Retained by Citigroup as trust-issued securities		5,300,000,000	11,900,000,000			1,300,000,000	1,400,000,000
Retained by Citigroup via non-certificated interests		19,300,000,000	44,600,000,000			100,000,000	200,000,000
Total ownership interests in principal amount of trust credit card receivables		46,700,000,000	79,400,000,000			1,500,000,000	1,700,000,000
Gains (losses) recognized on the securitization	0
Cash Flows Between Transferor and Transferee
Proceeds from new securitizations				900,000,000
Pay down of maturing notes				$ (8,900,000,000)	$ (5,000,000,000)			$ (100,000,000)