Restructuring and Asset Impairment Charges - Summary of Restructuring Activity (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Restructuring Reserve [Roll Forward]
Cash Payments	$ (6)	$ (14)
Strategic Growth Initiative Plan
Restructuring Reserve [Roll Forward]
Balance March 31, 2018	0
Net restructuring charges recognized	58
Non-cash charges	(20)
Cash Payments	(1)
Balance June 30, 2018	37
U.S. Pharmaceutical and Specialty Solutions | Strategic Growth Initiative Plan
Restructuring Reserve [Roll Forward]
Balance March 31, 2018	0
Net restructuring charges recognized	8
Non-cash charges	(4)
Cash Payments	(1)
Balance June 30, 2018	3
Medical-Surgical Solutions | Strategic Growth Initiative Plan
Restructuring Reserve [Roll Forward]
Balance March 31, 2018	0
Net restructuring charges recognized	12
Non-cash charges	0
Cash Payments	0
Balance June 30, 2018	12
Other | Strategic Growth Initiative Plan
Restructuring Reserve [Roll Forward]
Balance March 31, 2018	0
Net restructuring charges recognized	38
Non-cash charges	(16)
Cash Payments	0
Balance June 30, 2018	$ 22