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	Retained earnings		Treasury stock, at cost		Citigroup's accumulated other comprehensive income (loss)	Noncontrolling interests
Balance, beginning of period at Dec. 31, 2016				$ 19,253		$ 108,073	$ 146,477		$ (16,302)		$ (32,381)	$ 1,023
Adjustment to opening balance, net of taxes at Dec. 31, 2016	[1]						(660)				504
Adjusted balance, beginning of period at Dec. 31, 2016							145,817				(31,877)
Increase (Decrease) in Stockholders' Equity
Redemption of preferred stock				0
Employee benefit plans						(137)			526	[2]
Other						(9)	(90)	[3]				(61)
Citigroup’s net income		$ 12,136					12,095					41
Common dividends	[4]						(1,755)
Preferred dividends		(893)					(893)
Treasury stock acquired	[5]								(9,053)
Citigroup's total other comprehensive income (loss)											1,986	82
Transactions between noncontrolling-interest shareholders and the related consolidated subsidiary												(3)
Transactions between Citigroup and the noncontrolling-interest shareholders												(50)
Distributions paid to noncontrolling-interest shareholders												(44)
Net change in noncontrolling interests												(35)
Balance, end of period at Sep. 30, 2017		228,622	$ 227,634	19,253	$ 208,381	107,927	155,174		(24,829)		(29,891)	988
Balance, beginning of period at Jun. 30, 2017				19,253		107,829	152,178		(19,342)		(29,899)	1,088
Adjustment to opening balance, net of taxes at Jun. 30, 2017	[1]						0				0
Adjusted balance, beginning of period at Jun. 30, 2017							152,178				(29,899)
Increase (Decrease) in Stockholders' Equity
Employee benefit plans						102			3	[2]
Other						(4)	0	[3]				(9)
Citigroup’s net income		4,132					4,133					0
Common dividends	[4]						(865)
Preferred dividends		(272)					(272)
Treasury stock acquired	[5]								(5,490)
Citigroup's total other comprehensive income (loss)											8	12
Transactions between noncontrolling-interest shareholders and the related consolidated subsidiary												(3)
Transactions between Citigroup and the noncontrolling-interest shareholders												(56)
Distributions paid to noncontrolling-interest shareholders												(44)
Net change in noncontrolling interests												(100)
Balance, end of period at Sep. 30, 2017		228,622	227,634	19,253	208,381	107,927	155,174		(24,829)		(29,891)	988
Balance, beginning of period at Dec. 31, 2017		201,672		19,253		108,039	138,425		(30,309)		(34,668)	932
Adjustment to opening balance, net of taxes at Dec. 31, 2017	[1]						(84)				(3)
Adjusted balance, beginning of period at Dec. 31, 2017							138,341				(34,671)
Increase (Decrease) in Stockholders' Equity
Redemption of preferred stock				(218)
Employee benefit plans						(187)			477	[2]
Other						4	0	[3]				(12)
Citigroup’s net income		13,783					13,732					51
Common dividends	[4]						(2,777)
Preferred dividends		(860)					(860)
Treasury stock acquired	[5]								(9,846)
Citigroup's total other comprehensive income (loss)											(3,974)	(35)
Transactions between noncontrolling-interest shareholders and the related consolidated subsidiary												0
Transactions between Citigroup and the noncontrolling-interest shareholders												(39)
Distributions paid to noncontrolling-interest shareholders												(38)
Net change in noncontrolling interests												(73)
Balance, end of period at Sep. 30, 2018		197,863	197,004	19,035	177,969	107,856	148,436		(39,678)		(38,645)	859
Balance, beginning of period at Jun. 30, 2018				19,035		107,755	145,211		(34,413)		(37,494)	874
Adjustment to opening balance, net of taxes at Jun. 30, 2018	[1]						0				0
Adjusted balance, beginning of period at Jun. 30, 2018							145,211				(37,494)
Increase (Decrease) in Stockholders' Equity
Redemption of preferred stock				0
Employee benefit plans						98			6	[2]
Other						3	0	[3]				(1)
Citigroup’s net income		4,625					4,622					3
Common dividends	[4]						(1,127)
Preferred dividends		(270)					(270)
Treasury stock acquired	[5]								(5,271)
Citigroup's total other comprehensive income (loss)											(1,151)	8
Transactions between noncontrolling-interest shareholders and the related consolidated subsidiary												0
Transactions between Citigroup and the noncontrolling-interest shareholders												(23)
Distributions paid to noncontrolling-interest shareholders												(2)
Net change in noncontrolling interests												(15)
Balance, end of period at Sep. 30, 2018		$ 197,863	$ 197,004	$ 19,035	$ 177,969	$ 107,856	$ 148,436		$ (39,678)		$ (38,645)	$ 859

[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] Includes the impact of ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. See Note 1 to the Consolidated Financial Statements.

[4] Common dividends declared were $0.32 per share in the first and second quarters and $0.45 per share in the third quarter of 2018. Common dividends declared were $0.16 per share in the first and second quarters and $0.32 for the third quarter of 2017.

[5] For the three and nine months ended September 30, 2018 and 2017, primarily consists of open market purchases under Citi’s Board of Directors-approved common stock repurchase program.