SUBSIDIARY GUARANTEES - Summarized Income Statement (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Condensed Income Statements
Revenues, net of interest expense	$ 20,139	$ 18,508	$ 61,022	$ 57,332
Operating expense	13,511	12,749	40,370	38,307
Provision for credit losses	1,816	1,328	5,314	2,972
Income from continuing operations before income taxes	4,788	4,394	15,013	15,631
Provision (benefits) for income taxes	1,203	879	3,824	3,002
Citigroup’s net income	$ 3,546	$ 3,479	11,067	$ 12,332
Citigroup Inc. | Reportable legal entities
Condensed Income Statements
Revenues, net of interest expense			10,080
Operating expense			138
Provision for credit losses			0
Equity in undistributed income of subsidiaries			343
Income from continuing operations before income taxes			10,285
Provision (benefits) for income taxes			(782)
Citigroup’s net income			11,067
CGMHI | Reportable legal entities
Condensed Income Statements
Revenues, net of interest expense			8,494
Operating expense			8,856
Provision for credit losses			29
Equity in undistributed income of subsidiaries			0
Income from continuing operations before income taxes			(391)
Provision (benefits) for income taxes			5
Citigroup’s net income			$ (396)