Restructuring, Impairment, and Related Charges - Summary of Restructuring Charges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Restructuring Cost and Reserve [Line Items]
Severance and employee-related costs, net	$ (1)	$ 16	$ 13	$ 54
Exit and other-related costs	10	15	50	28
Asset impairments and accelerated depreciation	23	29	127	34
Total	32	60	190	116
Operating Segments | U.S. Pharmaceutical
Restructuring Cost and Reserve [Line Items]
Severance and employee-related costs, net	0	6	2	7
Exit and other-related costs	2	4	4	5
Asset impairments and accelerated depreciation	8	0	16	0
Total	10	10	22	12
Operating Segments | Prescription Technology Solutions
Restructuring Cost and Reserve [Line Items]
Severance and employee-related costs, net	(1)	0	(1)	0
Exit and other-related costs	1	0	2	0
Asset impairments and accelerated depreciation	0	0	17	0
Total	0	0	18	0
Operating Segments | Medical-Surgical Solutions
Restructuring Cost and Reserve [Line Items]
Severance and employee-related costs, net	1	3	1	3
Exit and other-related costs	0	(1)	2	2
Asset impairments and accelerated depreciation	1	1	5	1
Total	2	3	8	6
Operating Segments | International
Restructuring Cost and Reserve [Line Items]
Severance and employee-related costs, net	(2)	3	10	20
Exit and other-related costs	1	5	15	7
Asset impairments and accelerated depreciation	2	27	36	31
Total	1	35	61	58
Corporate
Restructuring Cost and Reserve [Line Items]
Severance and employee-related costs, net	1	4	1	24
Exit and other-related costs	6	7	27	14
Asset impairments and accelerated depreciation	12	1	53	2
Total	$ 19	$ 12	$ 81	$ 40