CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Citigroup’s net income (loss)		$ 19,401	$ 18,045	$ (6,798)
Add: Citigroup’s other comprehensive income (loss)
Net change in unrealized gains and losses on investment securities, net of taxes	[1],[2]	1,985	(1,089)	(863)
Net change in debt valuation adjustment (DVA), net of taxes	[2]	(1,136)	1,113	(569)
Net change in cash flow hedges, net of taxes		851	(30)	(138)
Benefit plans liability adjustment, net of taxes	[3]	(552)	(74)	(1,019)
Net change in foreign currency translation adjustment, net of taxes and hedges		(321)	(2,362)	(202)
Net change in excluded component of fair value hedges, net of taxes		25	(57)	0
Citigroup’s total other comprehensive income (loss)	[4]	852	(2,499)	(2,791)
Citigroup’s total comprehensive income (loss)		20,253	15,546	(9,589)
Add: Other comprehensive income (loss) attributable to noncontrolling interests		0	(43)	114
Add: Net income attributable to noncontrolling interests		66	35	60
Total comprehensive income (loss)		$ 20,319	$ 15,538	$ (9,415)

[1] For the years ended December 31, 2019 and 2018, amounts represent the net change in unrealized gains and losses on available-for-sale (AFS) debt securities. Effective January 1, 2018, the AFS category was 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.