CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Revenues	$ 62,599	$ 59,172	$ 179,086	$ 172,516
Cost of sales	(59,448)	(56,139)	(170,235)	(163,829)
Gross profit	3,151	3,033	8,851	8,687
Operating expenses	(2,291)	(2,535)	(6,625)	(6,779)
Claims and litigation charges, net	(8,067)	0	(7,936)	(82)
Goodwill impairment charges	0	(2)	(69)	(2)
Restructuring, impairment, and related charges	(155)	(136)	(271)	(204)
Total operating expenses	(10,513)	(2,673)	(14,901)	(7,067)
Operating income (loss)	(7,362)	360	(6,050)	1,620
Other income (expense), net	54	26	152	(15)
Equity earnings and charges from investment in Change Healthcare Joint Venture	0	(28)	0	(1,478)
Interest expense	(55)	(64)	(165)	(184)
Income (loss) from continuing operations before income taxes	(7,363)	294	(6,063)	(57)
Income tax benefit (expense)	1,189	(47)	1,011	111
Income (loss) from continuing operations	(6,174)	247	(5,052)	54
Loss from discontinued operations, net of tax	0	(5)	(1)	(12)
Net income (loss)	(6,174)	242	(5,053)	42
Net income attributable to noncontrolling interests	(52)	(56)	(152)	(163)
Net income (loss) attributable to McKesson Corporation	$ (6,226)	$ 186	$ (5,205)	$ (121)
Diluted
Continuing operations (in dollars per share)	$ (39.03)	$ 1.06	$ (32.28)	$ (0.60)
Discontinued operations (in dollars per share)	0	(0.03)	(0.01)	(0.06)
Total (in dollars per share)	(39.03)	1.03	(32.29)	(0.66)
Basic
Continuing operations (in dollars per share)	(39.03)	1.06	(32.28)	(0.60)
Discontinued operations (in dollars per share)	0	(0.02)	(0.01)	(0.06)
Total (in dollars per share)	$ (39.03)	$ 1.04	$ (32.29)	$ (0.66)
Weighted-average common shares outstanding
Diluted (in shares)	159.5	179.7	161.2	183.1
Basic (in shares)	159.5	178.7	161.2	183.1