CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Other Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury	Noncontrolling Interests
Beginning balance, common stock (in shares) at Mar. 31, 2015		384
Beginning balance at Mar. 31, 2015	$ 8,085	$ 4	$ 6,968	$ (7)	$ 12,705	$ (1,713)	$ (9,956)	$ 84
Beginning balance, treasury common stock (shares) at Mar. 31, 2015							(152)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans (in shares)		3					1
Issuance of shares under employee plans	14		123				$ (109)
Share-based compensation	130		130
Tax benefit related to issuance of shares under employee plans	117		117
Other comprehensive income (loss)	152					152
Net income	2,266				2,258			8
Repurchase of common stock (in shares)							(9)
Repurchase of common stock	(1,504)						$ (1,504)
Retirement of common stock (in shares)		116					116
Retirement of common stock		$ (1)	(1,493)		(6,354)		$ 7,848
Cash dividends declared	(249)				(249)
Other	(3)			5				(8)
Ending balance common stock (in shares) at Mar. 31, 2016		271
Ending balance at Mar. 31, 2016	9,008	$ 3	5,845	(2)	8,360	(1,561)	$ (3,721)	84
Ending balance, treasury common stock (shares) at Mar. 31, 2016							(46)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans (in shares)		3
Issuance of shares under employee plans	64		125				$ (61)
Share-based compensation	110		110
Tax benefit related to issuance of shares under employee plans	7				7
Acquisition of Vantage	89							89
Other comprehensive income (loss)	(580)					(580)
Net income	5,109				5,070			39
Repurchase of common stock (in shares)							(16)
Repurchase of common stock	(2,250)		(50)				$ (2,200)
Cash dividends declared	(249)				(249)
Other (in shares)		(1)
Other	(35)		(2)	0	1			(34)
Ending balance common stock (in shares) at Mar. 31, 2017		273
Ending balance at Mar. 31, 2017	$ 11,273	$ 3	6,028	(2)	13,189	(2,141)	$ (5,982)	178
Ending balance, treasury common stock (shares) at Mar. 31, 2017	(62)						(62)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans (in shares)		2
Issuance of shares under employee plans	$ 67		126				$ (59)
Share-based compensation	67		$ 67
Payments to noncontrolling interests	(98)							(98)
Other comprehensive income (loss)	424					424
Net income	254				67			187
Repurchase of common stock (in shares)			(36)				(11)
Repurchase of common stock	(1,650)						$ (1,614)
Exercise of put right by noncontrolling shareholders of McKesson Europe	3		$ 3
Cash dividends declared	(270)				(270)
Other (in shares)
Other	(13)			1				(14)
Ending balance common stock (in shares) at Mar. 31, 2018		275
Ending balance at Mar. 31, 2018	$ 10,057	$ 3	$ 6,188	$ (1)	$ 12,986	$ (1,717)	$ (7,655)	$ 253
Ending balance, treasury common stock (shares) at Mar. 31, 2018	(73)						(73)