CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenues	$ 238,228	$ 231,051	$ 214,319
Cost of sales	(226,080)	(219,028)	(202,565)
Gross profit	12,148	12,023	11,754
Operating expenses
Selling, distribution, general, and administrative expenses	(8,849)	(9,182)	(8,437)
Claims and litigation charges, net	(7,936)	(82)	(37)
Goodwill impairment charges	(69)	(2)	(1,797)
Restructuring, impairment, and related charges, net	(334)	(268)	(597)
Total operating expenses	(17,188)	(9,534)	(10,868)
Operating income (loss)	(5,040)	2,489	886
Other income, net	223	12	182
Equity earnings and charges from investment in Change Healthcare Joint Venture	0	(1,108)	(194)
Interest expense	(217)	(249)	(264)
Income (loss) from continuing operations before income taxes	(5,034)	1,144	610
Income tax benefit (expense)	695	(18)	(356)
Income (loss) from continuing operations	(4,339)	1,126	254
Income (loss) from discontinued operations, net of tax	(1)	(6)	1
Net income (loss)	(4,340)	1,120	255
Net income attributable to noncontrolling interests	(199)	(220)	(221)
Net income (loss) attributable to McKesson Corporation	$ (4,539)	$ 900	$ 34
Diluted
Continuing operations (in dollars per share)	$ (28.26)	$ 4.99	$ 0.17
Discontinued operations (in dollars per share)	0	(0.04)	0
Total (in dollars per share)	(28.26)	4.95	0.17
Basic
Continuing operations (in dollars per share)	(28.26)	5.01	0.17
Discontinued operations (in dollars per share)	0	(0.03)	0
Total (in dollars per share)	$ (28.26)	$ 4.98	$ 0.17
Weighted-average common shares outstanding
Diluted (in shares)	160.6	181.6	197.3
Basic (in shares)	160.6	180.6	196.3