CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury	Noncontrolling Interests
Beginning balance (in shares) at Mar. 31, 2021		273
Beginning balance (in shares) at Mar. 31, 2021						(115)
Beginning balance at Mar. 31, 2021	$ 175	$ 2	$ 6,925	$ 8,202	$ (1,480)	$ (13,670)	$ 196
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans, net of forfeitures (in shares)		2
Issuance of shares under employee plans, net of forfeitures	51		111			(60)
Share-based compensation	76		76
Repurchase of common stock	(1,280)		21			$ (1,301)
Repurchase of common stock (in shares)						(7)
Net income	835			753			82
Other comprehensive income (loss)	(15)				(15)
Cash dividends declared	(139)			(139)
Payments to noncontrolling interests	(79)						(79)
Exercise of put right by noncontrolling shareholders of McKesson Europe AG	8		178		(170)
Reclassification of McKesson Europe AG redeemable noncontrolling interests	287						287
Reclassification of recurring compensation to other accrued liabilities	(2)						(2)
Other	(4)			(4)
Ending balance (in shares) at Sep. 30, 2021		275
Ending balance (in shares) at Sep. 30, 2021						(122)
Ending balance at Sep. 30, 2021	(87)	$ 2	7,311	8,812	(1,665)	$ (15,031)	484
Beginning balance (in shares) at Jun. 30, 2021		274
Beginning balance (in shares) at Jun. 30, 2021						(119)
Beginning balance at Jun. 30, 2021	(45)	$ 2	7,057	8,618	(1,627)	$ (14,579)	484
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans, net of forfeitures (in shares)		1
Issuance of shares under employee plans, net of forfeitures	39		40			(1)
Share-based compensation	43		43
Repurchase of common stock	(280)		171			$ (451)
Repurchase of common stock (in shares)						(3)
Net income	310			267			43
Other comprehensive income (loss)	(38)				(38)
Cash dividends declared	(74)			(74)
Payments to noncontrolling interests	(40)						(40)
Reclassification of recurring compensation to other accrued liabilities	(2)						(2)
Other	0			1			(1)
Ending balance (in shares) at Sep. 30, 2021		275
Ending balance (in shares) at Sep. 30, 2021						(122)
Ending balance at Sep. 30, 2021	(87)	$ 2	7,311	8,812	(1,665)	$ (15,031)	484
Beginning balance (in shares) at Mar. 31, 2022		275
Beginning balance (in shares) at Mar. 31, 2022						(130)
Beginning balance at Mar. 31, 2022	(1,792)	$ 2	7,275	9,030	(1,534)	$ (17,045)	480
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans, net of forfeitures (in shares)		2
Issuance of shares under employee plans, net of forfeitures	(26)	$ 1	127			(154)
Share-based compensation	86		86
Repurchase of common stock	(1,524)		121			$ (1,645)
Repurchase of common stock (in shares)						(5)
Net income	1,776			1,694			82
Other comprehensive income (loss)	464				420		44
Cash dividends declared	(145)			(145)
Payments to noncontrolling interests	(77)						(77)
Reclassification of recurring compensation to other accrued liabilities	(4)						(4)
Other	(7)						(7)
Ending balance (in shares) at Sep. 30, 2022		277
Ending balance (in shares) at Sep. 30, 2022						(135)
Ending balance at Sep. 30, 2022	(1,249)	$ 3	7,609	10,579	(1,114)	$ (18,844)	518
Beginning balance (in shares) at Jun. 30, 2022		277
Beginning balance (in shares) at Jun. 30, 2022						(133)
Beginning balance at Jun. 30, 2022	(1,472)	$ 3	7,350	9,732	(948)	$ (18,141)	532
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans, net of forfeitures	34		36			(2)
Share-based compensation	46		46
Repurchase of common stock	(524)		177			$ (701)
Repurchase of common stock (in shares)						(2)
Net income	967			926			41
Other comprehensive income (loss)	(172)				(166)		(6)
Cash dividends declared	(78)			(78)
Payments to noncontrolling interests	(41)						(41)
Reclassification of recurring compensation to other accrued liabilities	(2)						(2)
Other	(7)			(1)			(6)
Ending balance (in shares) at Sep. 30, 2022		277
Ending balance (in shares) at Sep. 30, 2022						(135)
Ending balance at Sep. 30, 2022	$ (1,249)	$ 3	$ 7,609	$ 10,579	$ (1,114)	$ (18,844)	$ 518