Restructuring, Impairment, and Related Charges - Summary of Activity Related to Restructuring Liability (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Cost Alignment Plan
Beginning balance	$ 157	$ 237
Restructuring, impairment, and related charges	219	156	$ 352
Non-cash charges	(56)	(30)
Cash payments	(159)	(148)
Other	(10)	(58)
Ending balance	151	157	237
Operating Segments | U.S. Pharmaceutical
Cost Alignment Plan
Beginning balance	29	35
Restructuring, impairment, and related charges	21	23	61
Non-cash charges	0	(10)
Cash payments	(31)	(15)
Other	0	(4)
Ending balance	19	29	35
Operating Segments | International
Cost Alignment Plan
Beginning balance	66	129
Restructuring, impairment, and related charges	85	21	158
Non-cash charges	(46)	(6)
Cash payments	(31)	(45)
Other	(8)	(33)
Ending balance	66	66	129
Operating Segments | Medical-Surgical Solutions
Cost Alignment Plan
Beginning balance	22	26
Restructuring, impairment, and related charges	4	24	41
Non-cash charges	(1)	(1)
Cash payments	(21)	(26)
Other	(1)	(1)
Ending balance	3	22	26
Operating Segments | Prescription Technology Solutions
Cost Alignment Plan
Beginning balance	1	3
Restructuring, impairment, and related charges	4	(1)	3
Non-cash charges	0	0
Cash payments	(1)	(1)
Other	0	0
Ending balance	4	1	3
Corporate
Cost Alignment Plan
Beginning balance	39	44
Restructuring, impairment, and related charges	105	89	89
Non-cash charges	(9)	(13)
Cash payments	(75)	(61)
Other	(1)	(20)
Ending balance	59	39	$ 44
Other Accrued Liabilities
Cost Alignment Plan
Beginning balance	118
Ending balance	99	118
Other Noncurrent Liabilities
Cost Alignment Plan
Beginning balance	39
Ending balance	$ 52	$ 39