SECURITIZATIONS AND VARIABLE INTEREST ENTITIES (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	$ 8,932	$ 17,263
Liquidity facilities Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	4,128	12,262
Loan commitments Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	4,804	5,001
Citicorp
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	7,736	16,015
Citicorp | Liquidity facilities Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	4,128	12,249
Citicorp | Liquidity facilities Citigroup | Citi-administered asset-backed commercial paper conduits (ABCP)
Funding Commitments for Significant Unconsolidated VIEs
Notional amount		7,615
Citicorp | Liquidity facilities Citigroup | Asset-based financing
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	5	6
Citicorp | Liquidity facilities Citigroup | Municipal securities tender option bond trusts (TOBs)
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	4,123	4,628
Citicorp | Loan commitments Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	3,608	3,766
Citicorp | Loan commitments Citigroup | Asset-based financing
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	2,246	2,075
Citicorp | Loan commitments Citigroup | Municipal investments
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	1,335	1,669
Citicorp | Loan commitments Citigroup | Other
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	27	22
Citi Holdings
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	1,196	1,248
Citi Holdings | Liquidity facilities Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount		13
Citi Holdings | Liquidity facilities Citigroup | Collateralized loan obligations (CLOs)
Funding Commitments for Significant Unconsolidated VIEs
Notional amount		13
Citi Holdings | Loan commitments Citigroup
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	1,196	1,235
Citi Holdings | Loan commitments Citigroup | Asset-based financing
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	252	243
Citi Holdings | Loan commitments Citigroup | Municipal investments
Funding Commitments for Significant Unconsolidated VIEs
Notional amount	$ 944	$ 992