Restructuring, Impairment and Related Charges - Summary of Restructuring Activity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Restructuring Reserve [Roll Forward]
Beginning balance			$ 157
Restructuring, impairment, and related charges	$ 60	$ 45	116	$ 68
Non-cash charges			(34)
Cash payments			(77)
Other			(7)
Ending balance	155		155
Operating Segments | U.S. Pharmaceutical
Restructuring Reserve [Roll Forward]
Beginning balance			29
Restructuring, impairment, and related charges	10	3	12	2
Non-cash charges			0
Cash payments			(15)
Other			0
Ending balance	26		26
Operating Segments | International
Restructuring Reserve [Roll Forward]
Beginning balance			66
Restructuring, impairment, and related charges	35	12	58	16
Non-cash charges			(31)
Cash payments			(16)
Other			(1)
Ending balance	76		76
Operating Segments | Medical-Surgical Solutions
Restructuring Reserve [Roll Forward]
Beginning balance			22
Restructuring, impairment, and related charges	3	3	6	6
Non-cash charges			(1)
Cash payments			(11)
Other			(1)
Ending balance	15		15
Operating Segments | Prescription Technology Solutions
Restructuring Reserve [Roll Forward]
Beginning balance			1
Restructuring, impairment, and related charges	0	0	0	0
Non-cash charges			0
Cash payments			(1)
Other			0
Ending balance	0		0
Corporate
Restructuring Reserve [Roll Forward]
Beginning balance			39
Restructuring, impairment, and related charges	12	$ 27	40	$ 44
Non-cash charges			(2)
Cash payments			(34)
Other			(5)
Ending balance	38		38
Other accrued liabilities
Restructuring Reserve [Roll Forward]
Beginning balance			118
Ending balance	128		128
Other noncurrent liabilities
Restructuring Reserve [Roll Forward]
Beginning balance			39
Ending balance	$ 27		$ 27