Segments of Business - Segment Assets and Property, Plant and Equipment, Net by Geographical Area (Details) - USD ($) $ in Millions	Mar. 31, 2021	Mar. 31, 2020
Segment assets
Total assets	$ 65,015	$ 61,247
Long-lived assets
Total long-lived assets	3,094	2,765
United States
Long-lived assets
Total long-lived assets	2,110	1,873
Foreign
Long-lived assets
Total long-lived assets	984	892
Operating Segments | U.S. Pharmaceutical
Segment assets
Total assets	35,236	33,541
Operating Segments | International
Segment assets
Total assets	14,987	14,994
Operating Segments | Medical-Surgical Solutions
Segment assets
Total assets	5,986	5,395
Operating Segments | Prescription Technology Solutions
Segment assets
Total assets	3,446	3,786
Corporate
Segment assets
Total assets	$ 5,360	$ 3,531