CONDENSED PARENT COMPANY FINANCIAL STATEMENTS - Condensed Consolidating Statements of Income and Comprehensive Income (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues
Interest expense		$ 78,358	$ 25,740	$ 7,981
Net interest income		54,900	48,668	42,494
Commissions and fees		8,905	9,175	13,672
Principal transactions		10,948	14,159	10,154
Total non-interest revenues		23,562	26,670	29,390
Total revenues, net of interest expense		78,462	75,338	71,884
Operating expenses
Compensation and benefits		29,232	26,655	25,134
Total operating expenses		56,366	51,292	48,193
Income from continuing operations before income taxes		12,910	18,807	27,469
Provision (benefit) for income taxes		3,528	3,642	5,451
Net income		9,228	14,845	21,952
Comprehensive income
Add: Other comprehensive income (loss)	[1]	2,235	(8,297)	(6,707)
Total Citigroup comprehensive income		11,463	6,548	15,245
Parent Company
Revenues
Dividends from subsidiaries		16,811	8,992	6,482
Interest revenue—intercompany		6,955	4,628	3,757
Interest expense		6,339	5,250	4,791
Interest expense—intercompany		1,460	715	294
Net interest income		(844)	(1,337)	(1,328)
Commissions and fees		0	0	0
Commissions and fees—intercompany		(31)	(1)	(36)
Principal transactions		(928)	5,147	976
Principal transactions—intercompany		(771)	(5,686)	(1,375)
Other revenue		(23)	210	(64)
Other revenue—intercompany		(135)	(220)	(133)
Total non-interest revenues		(1,888)	(550)	(632)
Total revenues, net of interest expense		14,079	7,105	4,522
Operating expenses
Compensation and benefits		9	9	10
Compensation and benefits—intercompany		18	12	69
Other operating		160	85	83
Other operating—intercompany		15	15	11
Total operating expenses		202	121	173
Equity in undistributed income of subsidiaries		(5,572)	6,173	16,596
Income from continuing operations before income taxes		8,305	13,157	20,945
Provision (benefit) for income taxes		(923)	(1,688)	(1,007)
Net income		9,228	14,845	21,952
Comprehensive income
Add: Other comprehensive income (loss)		2,235	(8,297)	(6,707)
Total Citigroup comprehensive income		$ 11,463	$ 6,548	$ 15,245

[1] See Note 21.