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, 2017		273
Beginning balance at Mar. 31, 2017	$ 11,273	$ 3	$ 6,028	$ (2)	$ 13,189	$ (2,141)	$ (5,982)	$ 178
Beginning balance, treasury common stock (shares) at Mar. 31, 2017							(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)							(11)
Repurchase of common stock	(1,650)		(36)				$ (1,614)
Exercise of put right by noncontrolling shareholders of McKesson Europe	3		3
Cash dividends declared	(270)				(270)
Other (in shares)		0
Other	(13)		0	1	0			(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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans (in shares)		1
Issuance of shares under employee plans	63		75				$ (12)
Share-based compensation	92		92
Payments to noncontrolling interests	(184)							(184)
Other comprehensive income (loss)	(132)					(132)
Net income	210				34			176
Repurchase of common stock (in shares)							(13)
Repurchase of common stock	(1,627)		150				$ (1,777)
Retirement of common stock (in shares)		(5)					5
Retirement of common stock	0		(70)		(472)		$ 542
Cash dividends declared	(298)				(298)
Other (in shares)		0
Other	(48)		0	(1)	5			(52)
Ending balance common stock (in shares) at Mar. 31, 2019		271
Ending balance at Mar. 31, 2019	$ 8,287	$ 3	6,435	(2)	12,409	(1,849)	$ (8,902)	193
Ending balance, treasury common stock (shares) at Mar. 31, 2019	(81)						(81)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans (in shares)		1
Issuance of shares under employee plans	$ 93		113				$ (20)
Share-based compensation	115		115
Payments to noncontrolling interests	(154)							(154)
Other comprehensive income (loss)	146					146
Net income	1,078				900			178
Repurchase of common stock (in shares)							(14)
Repurchase of common stock	(1,934)		0				$ (1,934)
Change Healthcare share exchange (in shares)							(15)
Change Healthcare share exchange	(2,036)						$ (2,036)
Cash dividends declared	(294)				(294)
Other (in shares)		0
Other	(3)	$ (1)	0	2	(4)			0
Ending balance common stock (in shares) at Mar. 31, 2020		272
Ending balance at Mar. 31, 2020	$ 5,309	$ 2	$ 6,663	$ 0	$ 13,022	$ (1,703)	$ (12,892)	$ 217
Ending balance, treasury common stock (shares) at Mar. 31, 2020	(110)						(110)