CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Citigroup’s net income (loss)		$ 18,045	$ (6,798)	$ 14,912
Add: Citigroup’s other comprehensive income (loss)
Net change in unrealized gains and losses on investment securities, net of taxes	[1],[2]	(1,089)	(863)	108
Net change in debt valuation adjustment (DVA), net of taxes	[2]	1,113	(569)	(337)
Net change in cash flow hedges, net of taxes		(30)	(138)	57
Benefit plans liability adjustment, net of taxes	[3]	(74)	(1,019)	(48)
Net change in foreign currency translation adjustment, net of taxes and hedges		(2,362)	(202)	(2,802)
Net change in excluded component of fair value hedges, net of taxes		(57)	0	0
Citigroup’s total other comprehensive income (loss)	[4]	(2,499)	(2,791)	(3,022)
Citigroup’s total comprehensive income (loss)		15,546	(9,589)	11,890
Add: Other comprehensive income (loss) attributable to noncontrolling interests		(43)	114	(56)
Add: Net income attributable to noncontrolling interests		35	60	63
Total comprehensive income (loss)		$ 15,538	$ (9,415)	$ 11,897

[1] For the year ended December 31, 2018, amount represents the net change in unrealized gains and losses on available-for-sale (AFS) debt securities. Effective January 1, 2018, the AFS category is eliminated for equity securities under ASU 2016-01.

[2] See Note 1 to the Consolidated Financial Statements.

[3] See Note 8 to the Consolidated Financial Statements.

[4] Includes the impact of ASU 2018-02, adopted in 2017. See Note 1 to the Consolidated Financial Statements.