CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 494	$ 477
Other comprehensive income (loss), net of tax
Foreign currency translation adjustments	33	44
Unrealized gains (losses) on cash flow hedges	(5)	12
Changes in retirement-related benefit plans	1	21
Other comprehensive income, net of tax	29	77
Comprehensive income	523	554
Comprehensive income attributable to noncontrolling interests	(111)	(60)
Comprehensive income attributable to McKesson Corporation	$ 412	$ 494