Noncontrolling Interests and Redeemable Noncontrolling Interests - Schedule of Changes in Noncontrolling Interests and Redeemable Noncontrolling Interest (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	$ 367
Net income attributable to noncontrolling interests	158	$ 162	$ 173
Payments to noncontrolling interests	(152)	(150)	(155)
Reclassification of McKesson Europe AG redeemable noncontrolling interests			287
Formation of SCRI Oncology, LLC		247
Derecognition of noncontrolling interests in McKesson Europe		(382)
Ending balance	372	367
Noncontrolling Interests
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	367	480	196
Net income attributable to noncontrolling interests	158	162	165
Other comprehensive income		44	(4)
Payments to noncontrolling interests	(152)	(150)	(155)
Reclassification of recurring compensation to other accrued liabilities		(5)	(7)
Exercise of put right			0
Reclassification of McKesson Europe AG redeemable noncontrolling interests			287
Formation of SCRI Oncology, LLC		225
Derecognition of noncontrolling interests in McKesson Europe		(382)
Other	(1)	(7)	(2)
Ending balance	372	367	480
Redeemable Noncontrolling Interests
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Redeemable Noncontrolling Interest, Beginning balance	0	0	1,271
Net income (loss) attributable to redeemable noncontrolling interest	0	0	8
Other comprehensive income		0	3
Payments to noncontrolling interests	0	0	0
Reclassification of recurring compensation to other accrued liabilities		0	(8)
Exercise of put right			(983)
Reclassification of McKesson Europe AG redeemable noncontrolling interests			(287)
Formation of SCRI Oncology, LLC		0
Derecognition of noncontrolling interests in McKesson Europe		0
Other	0	0	(4)
Redeemable Noncontrolling Interest, Ending balance	$ 0	$ 0	$ 0