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 Loss	Treasury	Noncontrolling Interests	Opening retained earnings adjustments: adoption of new accounting standard	Opening retained earnings adjustments: adoption of new accounting standard Retained Earnings	Adjusted balance	Adjusted balance Common Stock	Adjusted balance Additional Paid-in Capital	Adjusted balance Other Capital	Adjusted balance Retained Earnings	Adjusted balance Accumulated Other Comprehensive Loss	Adjusted balance Treasury	Adjusted balance Noncontrolling Interests
Beginning balance, common stock (in shares) at Mar. 31, 2018		275										275
Beginning balance at Mar. 31, 2018	$ 10,057	$ 3	$ 6,188	$ (1)	$ 12,986	$ (1,717)	$ (7,655)	$ 253	$ 154	$ 154	$ 10,211	$ 3	$ 6,188	$ (1)	$ 13,140	$ (1,717)	$ (7,655)	$ 253
Beginning balance, treasury common stock (shares) at Mar. 31, 2018							(73)										(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 (loss)	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	(48)			(1)	5			(52)
Ending balance common stock (in shares) at Mar. 31, 2019		271										271
Ending balance at Mar. 31, 2019	8,287	$ 3	6,435	(2)	12,409	(1,849)	$ (8,902)	193	11	11	8,298	$ 3	6,435	(2)	12,420	(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 (loss)	1,078				900			178
Repurchase of common stock (in shares)							(14)
Repurchase of common stock	(1,934)						$ (1,934)
Change Healthcare share exchange (in shares)							(15)
Change Healthcare share exchange	(2,036)						$ (2,036)
Cash dividends declared	(294)				(294)
Other	(3)	$ (1)		2	(4)
Ending balance common stock (in shares) at Mar. 31, 2020		272										272
Ending balance at Mar. 31, 2020	$ 5,309	$ 2	6,663	0	13,022	(1,703)	$ (12,892)	217	$ (13)	$ (13)	$ 5,296	$ 2	$ 6,663	$ 0	$ 13,009	$ (1,703)	$ (12,892)	$ 217
Ending balance, treasury common stock (shares) at Mar. 31, 2020	(110)						(110)										(110)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans (in shares)		1
Issuance of shares under employee plans	$ 64		92				$ (28)
Share-based compensation	151		151
Payments to noncontrolling interests	(177)							(177)
Other comprehensive income (loss)	223					223
Net income (loss)	(4,383)				(4,539)			156
Exercise of put right by noncontrolling shareholders of McKesson Europe	3		3
Repurchase of common stock (in shares)							(5)
Repurchase of common stock	(750)						$ (750)
Cash dividends declared	(270)				(270)
Other	18		16		2
Ending balance common stock (in shares) at Mar. 31, 2021		273
Ending balance at Mar. 31, 2021	$ 175	$ 2	$ 6,925	$ 0	$ 8,202	$ (1,480)	$ (13,670)	$ 196
Ending balance, treasury common stock (shares) at Mar. 31, 2021	(115)						(115)