SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Assets and Liabilities of VIEs (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets of consolidated VIEs to be used to settle obligations of consolidated VIEs
Cash	$ 30,577	$ 27,515	$ 26,349
Trading account assets	334,114	331,945
Investments	526,582	512,822
Total loans	657,221	667,767
Allowance for credit losses on loans (ACLL)	(16,974)	(16,455)	(24,956)	$ (16,541)
Total loans, net	640,247	651,312
Other assets	103,743	101,551
Consolidated VIE / SPE assets	62,201	58,637
Liabilities of consolidated VIEs for which creditors or beneficial interest holders do not have recourse to the general credit of Citigroup
Short-term borrowings	47,096	27,973
Long-term debt	271,606	254,374
Other liabilities	87,873	74,920
Total liabilities	2,214,838	2,088,741
Consumer
Assets of consolidated VIEs to be used to settle obligations of consolidated VIEs
Total loans	368,067	376,534
Allowance for credit losses on loans (ACLL)	(14,119)	(14,040)	(20,180)	(14,630)
Corporate
Assets of consolidated VIEs to be used to settle obligations of consolidated VIEs
Total loans	289,154	291,233
Allowance for credit losses on loans (ACLL)	(2,855)	(2,415)	$ (4,776)	$ (1,911)
Variable Interest Entity, Primary Beneficiary
Assets of consolidated VIEs to be used to settle obligations of consolidated VIEs
Cash	61	260
Trading account assets	9,153	10,038
Investments	594	844
Total loans	54,808	48,989
Allowance for credit losses on loans (ACLL)	(2,520)	(2,668)
Total loans, net	52,288	46,321
Other assets	105	1,174
Liabilities of consolidated VIEs for which creditors or beneficial interest holders do not have recourse to the general credit of Citigroup
Short-term borrowings	9,807	8,376
Long-term debt	10,324	12,579
Other liabilities	622	694
Total liabilities	20,753	21,649
Variable Interest Entity, Primary Beneficiary | Consumer
Assets of consolidated VIEs to be used to settle obligations of consolidated VIEs
Total loans	35,026	34,677
Variable Interest Entity, Primary Beneficiary | Corporate
Assets of consolidated VIEs to be used to settle obligations of consolidated VIEs
Total loans	$ 19,782	$ 14,312