Earnings (Loss) 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		9 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	$ 630	$ 1,119	$ 2,330	$ 2,899
Net income attributable to noncontrolling interests	(41)	(41)	(119)	(123)
Income from continuing operations attributable to McKesson Corporation	589	1,078	2,211	2,776
Income (loss) from discontinued operations, net of tax	0	1	0	(3)
Net income attributable to McKesson Corporation	$ 589	$ 1,079	$ 2,211	$ 2,773
Weighted-average common shares outstanding:
Basic (in shares)	132.5	139.9	134.0	142.5
Diluted (in shares)	133.3	141.0	134.9	143.7
Diluted
Continuing operations (in usd per share)	$ 4.42	$ 7.65	$ 16.39	$ 19.32
Discontinued operations (in usd per share)	0	0.01	0	(0.02)
Total (in dollars per share)	4.42	7.66	16.39	19.30
Basic
Continuing operations (in usd per share)	4.45	7.70	16.49	19.48
Discontinued operations (in usd per share)	0	0.01	0	(0.02)
Total (in dollars per share)	$ 4.45	$ 7.71	$ 16.49	$ 19.46
Stock options
Weighted-average common shares outstanding:
Effect of dilutive securities (in shares)	0.1	0.2	0.2	0.3
Restricted stock units
Weighted-average common shares outstanding:
Effect of dilutive securities (in shares)	0.7	0.9	0.7	0.9