Earnings Per Common Share - Schedule of Computations for Basic and Diluted Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	$ 997	$ 807
Net income attributable to noncontrolling interests	(39)	(41)
Income from continuing operations attributable to McKesson Corporation	958	766
Income from discontinued operations, net of tax	0	2
Net income attributable to McKesson Corporation	$ 958	$ 768
Weighted-average common shares outstanding:
Basic (in shares)	135.5	144.2
Diluted (in shares)	136.6	145.9
Diluted
Continuing operations (in usd per share)	$ 7.02	$ 5.25
Discontinued operations (in usd per share)	0	0.01
Total (in dollars per share)	7.02	5.26
Basic
Continuing operations (in usd per share)	7.07	5.31
Discontinued operations (in usd per share)	0	0.01
Total (in dollars per share)	$ 7.07	$ 5.32
Stock options
Weighted-average common shares outstanding:
Effect of dilutive securities (in shares)	0.2	0.3
Restricted stock units
Weighted-average common shares outstanding:
Effect of dilutive securities (in shares)	0.9	1.4