CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 2,310	$ 1,543	$ 1,258
Other Comprehensive Income (Loss), Net of Tax
Foreign currency translation adjustments arising during the period	113	(1,855)	53
Unrealized losses on cash flow hedges arising during the period	9	(10)	(6)
Retirement-related benefit plans	50	(124)	36
Other Comprehensive Income (Loss), Net of Tax	172	(1,989)	83
Comprehensive Income (Loss)	2,482	(446)	1,341
Comprehensive (Income) Loss Attributable to Noncontrolling Interests	(72)	212	(16)
Comprehensive Income (Loss) Attributable to McKesson Corporation	$ 2,410	$ (234)	$ 1,325