Condensed Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Net Income	$ 411		$ 424
Other Comprehensive Income (Loss), Net of Tax
Foreign currency translation adjustments arising during period, net of income tax expense of nil and $2 (1)	98	[1]	(61)	[1]
Unrealized gains (losses) on cash flow hedges arising during period, net of income tax expense of nil and nil	(2)		1
Retirement-related benefit plans, net of income tax expense of $1 and $4	2		7
Other Comprehensive Income (Loss), Net of Tax	98		(53)
Comprehensive Income	509		371
Comprehensive Loss Attributable to Noncontrolling Interests	4		0
Comprehensive Income Attributable to McKesson	$ 513		$ 371

[1] The first quarter of 2015 includes net foreign currency translation loss of $12 million attributable to noncontrolling interests.