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
Increase (Decrease) in Stockholders' Equity
Redemption of preferred stock				0
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
Employee benefit plans						(426)			507	[2]
Preferred stock issuance expense						0
Other						(3)	(90)	[3]				(42)
Citigroup’s net income		$ 4,100					4,090					10
Common dividends	[4]						(445)
Preferred dividends		(301)					(301)
Treasury stock acquired	[5]								(1,784)
Citigroup's total other comprehensive income (loss)											1,464	31
Transactions between Citigroup and the noncontrolling-interest shareholders												(1)
Net change in noncontrolling interests												(2)
Balance, end of period at Mar. 31, 2017		228,997	$ 227,976	19,253	$ 208,723	107,644	149,071		(17,579)		(30,413)	1,021
Balance, beginning of period at Dec. 31, 2017		201,672		19,253		108,039	138,425		(30,309)		(34,668)	932
Increase (Decrease) in Stockholders' Equity
Redemption of preferred stock				(97)
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
Employee benefit plans						(405)			469	[2]
Preferred stock issuance expense						0
Other						(4)	0	[3]				(2)
Citigroup’s net income		4,642					4,620					22
Common dividends	[4]						(826)
Preferred dividends		(272)					(272)
Treasury stock acquired	[5]								(2,275)
Citigroup's total other comprehensive income (loss)											52	14
Transactions between Citigroup and the noncontrolling-interest shareholders												(15)
Net change in noncontrolling interests												19
Balance, end of period at Mar. 31, 2018		$ 202,866	$ 201,915	$ 19,156	$ 182,759	$ 107,630	$ 141,863		$ (32,115)		$ (34,619)	$ 951

[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 quarter of 2018 and $0.16 per share in the first quarter of 2017.

[5] For the three months ended March 31, 2018 and 2017, primarily consists of open market purchases under Citi’s Board of Directors-approved common stock repurchase program.