CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 627	$ (677)	$ 1,121	$ (200)
Other comprehensive income (loss), net of tax
Foreign currency translation adjustments	41	(32)	74	12
Unrealized gains (losses) on cash flow hedges	(19)	13	(24)	25
Changes in retirement-related benefit plans	(9)	75	(8)	96
Other comprehensive income (loss)	13	56	42	133
Comprehensive income (loss)	640	(621)	1,163	(67)
Comprehensive (income) loss attributable to noncontrolling interests	75	(35)	(36)	(95)
Comprehensive income (loss) attributable to McKesson Corporation	$ 715	$ (656)	$ 1,127	$ (162)