SUBSIDIARY GUARANTEES - Summarized Balance Sheet (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Condensed Balance Sheet Statements
Cash	$ 25,174	$ 27,342	$ 26,224
Securities borrowed and purchased under resale agreements	344,264	345,700
Trading account assets	431,468	411,756
Other assets	97,701	95,963
Total assets	2,432,510	2,411,834
Securities loaned and sold under repurchase agreements	299,387	278,107
Trading account liabilities	156,652	155,345
Short-term borrowings	31,910	37,457
Long-term debt	285,495	286,619
Other liabilities	71,492	75,835
Stockholders’ equity	207,398	206,251	$ 209,019
Total liabilities and equity	2,432,510	2,411,834
Citigroup Inc.
Condensed Balance Sheet Statements
Long-term debt	166,724	162,309
Citigroup Inc. | Reportable legal entities
Condensed Balance Sheet Statements
Cash	3,028	3,011
Securities borrowed and purchased under resale agreements	0	0
Trading account assets	403	461
Advances to subsidiaries	156,366	150,845
Other assets	15,574	14,202
Total assets	397,307	387,514
Securities loaned and sold under repurchase agreements	0	0
Trading account liabilities	171	300
Short-term borrowings	0	0
Long-term debt	166,724	162,309
Advances from subsidiaries	20,828	16,724
Other liabilities	2,999	2,728
Stockholders’ equity	206,585	205,453
Total liabilities and equity	397,307	387,514
Citigroup Inc. | Reportable legal entities | Subsidiary Holding Company
Condensed Balance Sheet Statements
Investments in subsidiaries	175,550	172,125
Citigroup Inc. | Reportable legal entities | Non-Bank Subsidiaries
Condensed Balance Sheet Statements
Investments in subsidiaries	46,386	46,870
CGMHI | Reportable legal entities
Condensed Balance Sheet Statements
Cash	22,608	23,756
Securities borrowed and purchased under resale agreements	284,284	283,174
Trading account assets	282,530	273,379
Advances to subsidiaries	0	0
Other assets	164,991	167,609
Total assets	754,413	747,918
Securities loaned and sold under repurchase agreements	314,919	309,862
Trading account liabilities	110,462	111,233
Short-term borrowings	23,502	20,481
Long-term debt	183,440	184,083
Advances from subsidiaries	0	0
Other liabilities	85,548	85,079
Stockholders’ equity	36,542	37,180
Total liabilities and equity	754,413	747,918
CGMHI | Reportable legal entities | Subsidiary Holding Company
Condensed Balance Sheet Statements
Investments in subsidiaries	0	0
CGMHI | Reportable legal entities | Non-Bank Subsidiaries
Condensed Balance Sheet Statements
Investments in subsidiaries	$ 0	$ 0