DEBT (Details 2) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012 series	Dec. 31, 2011
Long-Term Debt:
Number of series of trust preferred securities redeemed		3
Pretax gain on redemption of trust preferred securities	$ 198,000,000
Total long-term debt	271,862,000,000	271,862,000,000	323,505,000,000
Federal Deposit Insurance Corporation (FDIC)
Aggregate annual maturities of long-term debt obligations
2012	13,500,000,000	13,500,000,000
Junior subordinated notes relating to trust preferred securities
Long-Term Debt:
Total long-term debt	10,560,000,000	10,560,000,000	16,057,000,000
Citigroup Parent Company
Long-Term Debt:
Total long-term debt	154,333,000,000	154,333,000,000	181,702,000,000
Bank
Long-Term Debt:
Total long-term debt	61,887,000,000	61,887,000,000	77,895,000,000
Collateralized long-term advances from Federal Home Loan Bank	17,300,000,000	17,300,000,000	11,000,000,000
Citigroup Global Markets Holdings Inc. (CGMHI) | Revolving line of credit facility
Long-Term Debt:
Amount drawn down on long-term financing facilities with unaffiliated banks	300,000,000	300,000,000
Notice period banks are required to give CGMHI prior to terminating financing facilities		1 year
Non-bank
Long-Term Debt:
Total long-term debt	55,642,000,000	55,642,000,000	63,908,000,000
Citigroup Funding Inc. (CFI)
Long-Term Debt:
Carrying value of Principal-Protected Trust Securities	$ 170,000,000	$ 170,000,000	$ 215,000,000