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	107		174			(67)
Share-based compensation	112		112
Repurchase of common stock	(2,008)		21			$ (2,029)
Repurchase of common stock (in shares)						(10)
Net income (loss)	874			746			128
Other comprehensive income (loss)	(7)				(5)		(2)
Cash dividends declared	(211)			(211)
Payments to noncontrolling interests	(117)						(117)
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	(5)						(5)
Other	(2)		1	(3)
Ending balance (in shares) at Dec. 31, 2021		275
Ending balance (in shares) at Dec. 31, 2021						(125)
Ending balance at Dec. 31, 2021	(787)	$ 2	7,411	8,734	(1,655)	$ (15,766)	487
Beginning balance (in shares) at Sep. 30, 2021		275
Beginning balance (in shares) at Sep. 30, 2021						(122)
Beginning balance at Sep. 30, 2021	(87)	$ 2	7,311	8,812	(1,665)	$ (15,031)	484
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans, net of forfeitures	56		63			(7)
Share-based compensation	36		36
Repurchase of common stock	(728)					$ (728)
Repurchase of common stock (in shares)						(3)
Net income (loss)	39			(7)			46
Other comprehensive income (loss)	8				10		(2)
Cash dividends declared	(72)			(72)
Payments to noncontrolling interests	(38)						(38)
Reclassification of recurring compensation to other accrued liabilities	(3)						(3)
Other	2		1	1
Ending balance (in shares) at Dec. 31, 2021		275
Ending balance (in shares) at Dec. 31, 2021						(125)
Ending balance at Dec. 31, 2021	(787)	$ 2	7,411	8,734	(1,655)	$ (15,766)	487
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	(13)	$ 1	143			(157)
Share-based compensation	122		122
Repurchase of common stock	(3,500)		(25)			$ (3,475)
Repurchase of common stock (in shares)						(10)
Net income (loss)	2,896			2,773			123
Other comprehensive income (loss)	679				635		44
Cash dividends declared	(222)			(222)
Payments to noncontrolling interests	(113)						(113)
Reclassification of recurring compensation to other accrued liabilities	(5)						(5)
Formation of an oncology research business	247		22				225
Derecognition of noncontrolling interests in McKesson Europe	(382)						(382)
Other	(6)		(1)	1			(6)
Ending balance (in shares) at Dec. 31, 2022		277
Ending balance (in shares) at Dec. 31, 2022						(140)
Ending balance at Dec. 31, 2022	(2,089)	$ 3	7,536	11,582	(899)	$ (20,677)	366
Beginning balance (in shares) at Sep. 30, 2022		277
Beginning balance (in shares) at Sep. 30, 2022						(135)
Beginning balance at Sep. 30, 2022	(1,249)	$ 3	7,609	10,579	(1,114)	$ (18,844)	518
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employee plans, net of forfeitures	13		16			(3)
Share-based compensation	36		36
Repurchase of common stock	(1,976)		(146)			$ (1,830)
Repurchase of common stock (in shares)						(5)
Net income (loss)	1,120			1,079			41
Other comprehensive income (loss)	215				215
Cash dividends declared	(77)			(77)
Payments to noncontrolling interests	(36)						(36)
Reclassification of recurring compensation to other accrued liabilities	(1)						(1)
Formation of an oncology research business	247		22				225
Derecognition of noncontrolling interests in McKesson Europe	(382)						(382)
Other	1		(1)	1			1
Ending balance (in shares) at Dec. 31, 2022		277
Ending balance (in shares) at Dec. 31, 2022						(140)
Ending balance at Dec. 31, 2022	$ (2,089)	$ 3	$ 7,536	$ 11,582	$ (899)	$ (20,677)	$ 366