CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - USD ($) $ in Millions		Total IBM Stockholders' Equity	Common Stock and Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income/(Loss)	Non-Controlling Interests	Total
Balance at the Beginning of the Period at Dec. 31, 2016		$ 18,246	$ 53,935	$ 152,759	$ (159,050)	$ (29,398)	$ 146	$ 18,392
Equity
Cumulative effect of change in accounting principle | Accounting Standards Update 2016-16, Intra-Entity Transfers of Assets Other Than Inventory	[1]	102		102				102
Net income plus other comprehensive income/(loss)
Net income		1,750		1,750				1,750
Other comprehensive income/(loss)		688				688		688
Total comprehensive income/(loss)		2,438						2,438
Cash dividends paid - common stock		(1,321)		(1,321)				(1,321)
Common stock issued under employee plans (Shares - 1,037,255 and 1,059,160 for 2018 and 2017, respectively)		169	169					169
Purchases (Shares - 325,635 and 289,364) and sales (Shares - 45,878 and 43,179) of treasury stock under employee plans - net, for 2018 and 2017, respectively		(44)		1	(45)			(44)
Other treasury shares purchased, not retired (Shares - 4,968,417 and 7,183,494 for 2018 and 2017, respectively)		(1,264)			(1,264)			(1,264)
Changes in noncontrolling interests							(25)	(25)
Balance at the End of the Period at Mar. 31, 2017		18,327	54,104	153,292	(160,359)	(28,710)	121	18,448
Balance at the Beginning of the Period at Dec. 31, 2017		17,594	54,566	153,126	(163,507)	(26,592)	131	17,725
Equity
Cumulative effect of change in accounting principle | Accounting Standards Update 2014-09, Revenue from Contracts with Customers		524		524				524
Cumulative effect of change in accounting principle | Accounting Standards Updates 2016-01 (Financial Instruments), 2017-12 (Hedging) and 2018-02 (Stranded Tax Effects)	[2]			2,422		(2,422)
Net income plus other comprehensive income/(loss)
Net income		1,679		1,679				1,679
Other comprehensive income/(loss)		430				430		430
Total comprehensive income/(loss)		2,109						2,109
Cash dividends paid - common stock		(1,382)		(1,382)				(1,382)
Common stock issued under employee plans (Shares - 1,037,255 and 1,059,160 for 2018 and 2017, respectively)		146	146					146
Purchases (Shares - 325,635 and 289,364) and sales (Shares - 45,878 and 43,179) of treasury stock under employee plans - net, for 2018 and 2017, respectively		(45)		1	(47)			(45)
Other treasury shares purchased, not retired (Shares - 4,968,417 and 7,183,494 for 2018 and 2017, respectively)		(780)			(780)			(780)
Changes in noncontrolling interests							(7)	(7)
Balance at the End of the Period at Mar. 31, 2018		$ 18,166	$ 54,712	$ 156,371	$ (164,334)	$ (28,583)	$ 124	$ 18,290

[1] Reflects the adoption of the FASB guidance on intra-entity transfers of assets.

[2] Reflects the adoption of the FASB guidance on stranded tax effects, hedging and financial instruments. Refer to note 2, "Accounting Changes".