SECURITIZATIONS AND VARIABLE INTEREST ENTITIES (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	$ 16,407	$ 17,263
Liquidity facilities Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	11,876
Loan commitments Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	4,531
Citicorp
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	15,189	16,015
Citicorp | Liquidity facilities Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	11,860
Citicorp | Liquidity facilities Citigroup | Citi-administered asset-backed commercial paper conduits (ABCP)
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	7,263
Citicorp | Liquidity facilities Citigroup | Asset-based financing
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	6
Citicorp | Liquidity facilities Citigroup | Municipal securities tender option bond trusts (TOBs)
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	4,591
Citicorp | Loan commitments Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	3,329
Citicorp | Loan commitments Citigroup | Asset-based financing
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	1,643
Citicorp | Loan commitments Citigroup | Municipal investments
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	1,661
Citicorp | Loan commitments Citigroup | Other
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	25
Citi Holdings
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	1,218	1,248
Citi Holdings | Liquidity facilities Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	16
Citi Holdings | Liquidity facilities Citigroup | Collateralized loan obligations (CLOs)
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	16
Citi Holdings | Loan commitments Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	1,202
Citi Holdings | Loan commitments Citigroup | Asset-based financing
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	237
Citi Holdings | Loan commitments Citigroup | Municipal investments
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	$ 965