SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Asset-Backed Commercial Paper Conduits (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Classification of Other Securitization Details
Commercial paper	$ 20,922,000,000	$ 25,530,000,000
Citi-administered asset-backed commercial paper conduits
Classification of Other Securitization Details
Purchased assets outstanding under conduits	18,600,000,000	19,600,000,000
Incremental funding commitments with clients	$ 16,100,000,000	$ 13,900,000,000
Weighted average life of commercial paper issued by conduits	66 days	64 days
Citi-administered asset-backed commercial paper conduits | Minimum
Classification of Other Securitization Details
Letters of credit as percentage of conduit assets	8.00%
Floor price of conduit's assets	$ 350,000,000
Citi-administered asset-backed commercial paper conduits | Maximum
Classification of Other Securitization Details
Letters of credit as percentage of conduit assets	10.00%
Citi-administered asset-backed consolidated commercial paper conduits (ABCP)
Classification of Other Securitization Details
Letters of credit provided to conduits	$ 1,900,000,000	$ 1,900,000,000
Commercial paper	$ 7,700,000,000	$ 8,600,000,000