Restructuring, Impairment, and Related Charges - Summary of Restructuring Activity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Restructuring Reserve [Roll Forward]
Beginning balance			$ 151
Restructuring, impairment, and related charges	$ 32	$ 60	190	$ 116
Non-cash charges			(127)
Cash payments			(41)
Other			(12)
Ending balance	161		161
Operating Segments | U.S. Pharmaceutical
Restructuring Reserve [Roll Forward]
Beginning balance			19
Restructuring, impairment, and related charges	10	10	22	12
Non-cash charges			(16)
Cash payments			(9)
Other			0
Ending balance	16		16
Operating Segments | Prescription Technology Solutions
Restructuring Reserve [Roll Forward]
Beginning balance			4
Restructuring, impairment, and related charges	0	0	18	0
Non-cash charges			(17)
Cash payments			(1)
Other			0
Ending balance	4		4
Operating Segments | Medical-Surgical Solutions
Restructuring Reserve [Roll Forward]
Beginning balance			3
Restructuring, impairment, and related charges	2	3	8	6
Non-cash charges			(5)
Cash payments			(4)
Other			0
Ending balance	2		2
Operating Segments | International
Restructuring Reserve [Roll Forward]
Beginning balance			66
Restructuring, impairment, and related charges	1	35	61	58
Non-cash charges			(36)
Cash payments			(14)
Other			(6)
Ending balance	71		71
Corporate
Restructuring Reserve [Roll Forward]
Beginning balance			59
Restructuring, impairment, and related charges	19	$ 12	81	$ 40
Non-cash charges			(53)
Cash payments			(13)
Other			(6)
Ending balance	68		68
Other accrued liabilities
Restructuring Reserve [Roll Forward]
Beginning balance			99
Ending balance	95		95
Liabilities held for sale
Restructuring Reserve [Roll Forward]
Ending balance	36		36
Other noncurrent liabilities
Restructuring Reserve [Roll Forward]
Beginning balance			52
Ending balance	$ 30		$ 30