DEBT (Details 2) (USD $)										3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Federal Deposit Insurance Corporation (FDIC)	Mar. 31, 2012 Junior subordinated notes relating to trust preferred securities	Dec. 31, 2011 Junior subordinated notes relating to trust preferred securities	Mar. 31, 2012 Citigroup Parent Company	Dec. 31, 2011 Citigroup Parent Company	Mar. 31, 2012 Bank	Dec. 31, 2011 Bank	Mar. 31, 2012 Citigroup Global Markets Holdings Inc. (CGMHI) Revolving line of credit facility	Mar. 31, 2012 Non-bank	Dec. 31, 2011 Non-bank	Mar. 31, 2012 Citigroup Funding Inc. (CFI)	Dec. 31, 2011 Citigroup Funding Inc. (CFI)
Long-Term Debt:
Total long-term debt	$ 311,079,000,000	$ 323,505,000,000		$ 16,041,000,000	$ 16,057,000,000	$ 176,080,000,000	$ 181,702,000,000	$ 70,660,000,000	$ 76,544,000,000		$ 64,339,000,000	$ 65,259,000,000
Collateralized advances from Federal Home Loan Bank, long-term								11,000,000,000	11,000,000,000
Carrying value of Principal-Protected Trust Securities													219,000,000	176,000,000
Amount drawn down on long-term financing facilities with unaffiliated banks										700,000,000
Amount drawn down on long-term financing facilities guaranteed by Citigroup										150,000,000
Notice period banks are required to give CGMHI prior to terminating financing facilities (in years)										1 year
Aggregate annual maturities of long-term debt obligations
2012			$ 34,500,000,000