CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions		Total	Citigroup stockholders' equity	Preferred stock at aggregate liquidation value	Citigroup common stockholders' equity	Common stock and additional paid-in capital (APIC)	Retained earnings	Retained earnings Variable post-charge-off third-party collection costs	[1]	Retained earnings Cumulative Effect, Period of Adoption, Adjustment	[1]	Retained earnings Cumulative Effect, Period of Adoption, Adjusted Balance	Treasury stock, at cost		Citigroup's accumulated other comprehensive income (loss)	Noncontrolling interests
Balance, beginning of period at Dec. 31, 2019				$ 17,980		$ 107,871	$ 165,369	$ 330		$ (3,076)		$ 162,623	$ (61,660)		$ (36,318)	$ 704
Increase (Decrease) in Stockholders' Equity
Issuance of new preferred stock				1,500
Redemption of preferred stock				(1,500)
Employee benefit plans						(174)							442	[2]
Preferred stock issuance costs (new issuances, net of reclassifications to retained earnings for redemptions)						2
Other (primarily reclassifications from APIC for preferred issuance costs on redemptions)							(4)
Common dividends	[3]						(2,152)
Preferred dividends		$ (544)					(544)
Treasury stock acquired	[4]												(2,925)
Transactions between Citigroup and the noncontrolling-interest shareholders																(6)
Citigroup’s total other comprehensive income															2,973	(12)
Net income before attribution of noncontrolling interests		3,586					3,592									(6)
Net change in noncontrolling interests																(24)
Balance, end of period at Jun. 30, 2020		192,386	$ 191,706	17,980	$ 173,726	107,699	163,515						(64,143)		(33,345)	680
Balance, beginning of period at Mar. 31, 2020				17,980		107,581	163,782					163,782	(64,147)		(32,521)	651
Increase (Decrease) in Stockholders' Equity
Employee benefit plans						118							4	[2]
Other (primarily reclassifications from APIC for preferred issuance costs on redemptions)							1									(10)
Common dividends	[3]						(1,071)
Preferred dividends		(253)					(253)
Citigroup’s total other comprehensive income															(824)	39
Net income before attribution of noncontrolling interests		1,056					1,056
Net change in noncontrolling interests																29
Balance, end of period at Jun. 30, 2020		192,386	191,706	17,980	173,726	107,699	163,515						(64,143)		(33,345)	680
Balance, beginning of period at Dec. 31, 2020		200,200		19,480		107,877	168,272					168,272	(64,129)		(32,058)	758
Balance, end of period at Mar. 31, 2021				20,280		107,725	174,816					174,816	(65,261)		(35,011)	724
Balance, beginning of period at Dec. 31, 2020		200,200		19,480		107,877	168,272					168,272	(64,129)		(32,058)	758
Increase (Decrease) in Stockholders' Equity
Issuance of new preferred stock				2,300
Redemption of preferred stock				(3,785)
Employee benefit plans						(63)							476	[2]
Preferred stock issuance costs (new issuances, net of reclassifications to retained earnings for redemptions)						40
Other (primarily reclassifications from APIC for preferred issuance costs on redemptions)						(3)	(40)									(11)
Common dividends	[3]						(2,136)
Preferred dividends		(545)					(545)
Treasury stock acquired	[4]												(4,600)
Transactions between Citigroup and the noncontrolling-interest shareholders																1
Citigroup’s total other comprehensive income															(3,062)	(40)
Net income before attribution of noncontrolling interests		14,178					14,135									43
Net change in noncontrolling interests																(7)
Balance, end of period at Jun. 30, 2021		202,910	202,159	17,995	184,164	107,851	179,686						(68,253)		(35,120)	751
Balance, beginning of period at Mar. 31, 2021				20,280		107,725	174,816					$ 174,816	(65,261)		(35,011)	724
Increase (Decrease) in Stockholders' Equity
Redemption of preferred stock				(2,285)
Employee benefit plans						112							8	[2]
Preferred stock issuance costs (new issuances, net of reclassifications to retained earnings for redemptions)						8
Other (primarily reclassifications from APIC for preferred issuance costs on redemptions)						6	(8)									(2)
Common dividends	[3]						(1,062)
Preferred dividends		(253)					(253)
Treasury stock acquired	[4]												(3,000)
Transactions between Citigroup and the noncontrolling-interest shareholders																1
Citigroup’s total other comprehensive income															(109)	18
Net income before attribution of noncontrolling interests		6,203					6,193									10
Net change in noncontrolling interests																27
Balance, end of period at Jun. 30, 2021		$ 202,910	$ 202,159	$ 17,995	$ 184,164	$ 107,851	$ 179,686						$ (68,253)		$ (35,120)	$ 751

[1] See Note 1 to the Consolidated Financial Statements for additional details.

[2] Includes treasury stock related to (i) certain activity on employee stock option program exercises where the employee delivers existing shares to cover the option exercise, or (ii) under Citi’s employee restricted or deferred stock programs where shares are withheld to satisfy tax requirements.

[3] Common dividends declared were $0.51 per share in both of the first and second quarters of 2021 and 2020.

[4] Primarily consists of open market purchases under Citi’s Board of Directors-approved common share repurchase program.