CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 526	$ 961	$ 999	$ 1,382
Other Comprehensive Income (Loss), Net of Tax
Foreign currency translation adjustments arising during the period	(113)	11	(216)	588
Unrealized gains (losses) on cash flow hedges arising during the period	35	(16)	37	(5)
Retirement-related benefit plans	3	1	15	(7)
Other Comprehensive Income (Loss), Net of Tax	(75)	(4)	(164)	576
Comprehensive Income	451	957	835	1,958
Comprehensive Income Attributable to Noncontrolling Interests	(46)	(70)	(114)	(330)
Comprehensive Income Attributable to McKesson Corporation	$ 405	$ 887	$ 721	$ 1,628