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, 2024	Jun. 30, 2023
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income	$ 960	$ 997
Net income attributable to noncontrolling interests	(45)	(39)
Net income attributable to McKesson Corporation	$ 915	$ 958
Weighted-average common shares outstanding:
Basic (in shares)	129.8	135.5
Diluted (in shares)	130.7	136.6
Earnings (loss) per common share attributable to McKesson Corporation:
Diluted (in usd per share)	$ 7.00	$ 7.02
Basic (in usd per share)	$ 7.04	$ 7.07
Stock options
Weighted-average common shares outstanding:
Effect of dilutive securities (in shares)	0.1	0.2
Restricted stock units
Weighted-average common shares outstanding:
Effect of dilutive securities (in shares)	0.8	0.9