CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 1,287	$ (4,340)	$ 1,120
Other comprehensive income, net of tax
Foreign currency translation adjustments	60	184	(66)
Unrealized gains (losses) on cash flow hedges	14	(36)	86
Changes in retirement-related benefit plans	41	22	129
Other comprehensive income, net of tax	115	170	149
Comprehensive income (loss)	1,402	(4,170)	1,269
Comprehensive income attributable to noncontrolling interests	(172)	(146)	(223)
Comprehensive income (loss) attributable to McKesson Corporation	$ 1,230	$ (4,316)	$ 1,046