SUBSIDIARY GUARANTEES - Summarized Income Statement (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Condensed Income Statements
Revenues, net of interest expense	$ 21,104	$ 21,447
Total operating expenses	14,195	13,289
Provision for credit losses	2,422	1,737
Income from continuing operations before income taxes	4,544	6,183
Provision (benefits) for income taxes	1,136	1,531
Citigroup’s net income	3,371	$ 4,606
Citigroup Inc. | Reportable legal entities
Condensed Income Statements
Revenues, net of interest expense	(599)
Total operating expenses	64
Provision for credit losses	0
Equity in undistributed income of subsidiaries	3,950
Income from continuing operations before income taxes	3,287
Provision (benefits) for income taxes	(84)
Citigroup’s net income	3,371
CGMHI | Reportable legal entities
Condensed Income Statements
Revenues, net of interest expense	3,102
Total operating expenses	3,122
Provision for credit losses	22
Equity in undistributed income of subsidiaries	0
Income from continuing operations before income taxes	(42)
Provision (benefits) for income taxes	21
Citigroup’s net income	$ (63)