CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Millions	3 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Total Revenues	$ 55,728,000,000	$ 52,607,000,000
Cost of Sales	(52,941,000,000)	(49,828,000,000)
Gross Profit	2,787,000,000	2,779,000,000
Operating Expenses	(2,130,000,000)	(2,127,000,000)
Goodwill Impairment Charges	0	(570,000,000)
Restructuring and Asset Impairment Charges	(23,000,000)	(96,000,000)
Gain from Escrow Settlement	0	97,000,000
Total Operating Expenses	(2,153,000,000)	(2,696,000,000)
Operating Income	634,000,000	83,000,000
Other Income, Net	37,000,000	40,000,000
Income (Loss) from Equity Method Investment in Change Healthcare Joint Venture	4,000,000	(56,000,000)
Interest Expense	(56,000,000)	(61,000,000)
Income from Continuing Operations Before Income Taxes	619,000,000	6,000,000
Income Tax Expense	(136,000,000)	(87,000,000)
Income (Loss) from Continuing Operations	483,000,000	(81,000,000)
Income (Loss) from Discontinued Operations, Net of Tax	(6,000,000)	1,000,000
Net Income (Loss)	477,000,000	(80,000,000)
Net Income Attributable to Noncontrolling Interests	(54,000,000)	(58,000,000)
Net Income (Loss) Attributable to McKesson Corporation	$ 423,000,000	$ (138,000,000)
Diluted
Continuing operations (in dollars per share)	$ 2.27	$ (0.69)
Discontinued operations (in dollars per share)	(0.03)	0.01
Total (in dollars per share)	2.24	(0.68)
Basic
Continuing operations (in dollars per share)	2.28	(0.69)
Discontinued operations (in dollars per share)	(0.03)	0.01
Total (in dollars per share)	2.25	(0.68)
Dividends declared per common share (in dollars per share)	$ 0.39	$ 0.34
Weighted Average Common Shares
Diluted (in shares)	189	202
Basic (in shares)	188	202