EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Antidilutive Securities Excluded from Computation of Earnings Per Share
Income from continuing operations before attribution of noncontrolling interests		$ 3,791	$ 3,274	$ 11,932	$ 9,945
Noncontrolling interests		38	35	95	117
Net income from continuing operations (for EPS purposes)		3,753	3,239	11,837	9,828
Income (loss) from discontinued operations, net of taxes		(1)	(1)	(2)	(2)
Citigroup’s net income		3,752	3,238	11,835	9,826
Less: Preferred dividends		274	277	830	798
Net income available to common shareholders		3,478	2,961	11,005	9,028
Less: Dividends and undistributed earnings allocated to employee restricted and deferred shares with rights to dividends, and other relevant items, applicable to basic EPS		40	56	133	133
Net income allocated to common shareholders for basic EPS		$ 3,438	$ 2,905	$ 10,872	$ 8,895
Weighted-average common shares outstanding applicable to basic EPS (in shares)		1,820.3	1,899.9	1,851.7	1,906.0
Basic earnings per share
Income from continuing operations (in dollars per share)	[1]	$ 1.89	$ 1.53	$ 5.87	$ 4.67
Discontinued operations (in dollars per share)	[1]	0	0	0	0
Net income (in dollars per share)	[1]	$ 1.89	$ 1.53	$ 5.87	$ 4.67
Add back: Dividends allocated to employee restricted and deferred shares with rights to dividends that are forfeitable		$ 20	$ 20	$ 56	$ 54
Net income allocated to common shareholders for diluted EPS		$ 3,458	$ 2,925	$ 10,928	$ 8,949
Effect of dilutive securities
Other employee plans (in shares)		42.3	40.4	40.1	37.1
Adjusted weighted-average common shares outstanding applicable to diluted EPS (in shares)		1,862.6	1,940.3	1,891.8	1,943.1
Diluted earnings per share
Income from continuing operations (in dollars per share)	[1]	$ 1.86	$ 1.51	$ 5.78	$ 4.61
Discontinued operations (in dollars per share)	[1]	0	0	0	0
Net income (in dollars per share)	[1]	$ 1.86	$ 1.51	$ 5.78	$ 4.61
Income allocated to employees with no rights to dividends		$ 40

[1] Due to rounding, earnings per share on continuing operations and discontinued operations may not sum to earnings per share on net income.