Goodwill Impairment Charges (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018
Goodwill [Line Items]
Goodwill and asset impairment charges	$ 570	$ 0
Goodwill	10,585		$ 10,924
European Pharmaceutical Solutions
Goodwill [Line Items]
Goodwill and asset impairment charges	570
Goodwill	1,213		$ 1,850
Consumer Solutions and Pharmacy Solutions Reporting Units [Member]
Goodwill [Line Items]
Goodwill and asset impairment charges	$ 332
Consumer Solutions Reporting Unit
Goodwill [Line Items]
Discount rate (percent)	8.50%
Terminal growth rate (percent)	1.25%
Goodwill	$ 462
Pharnacy Solutions Reporting Unit
Goodwill [Line Items]
Goodwill and asset impairment charges	$ 238
Discount rate (percent)	8.00%
Terminal growth rate (percent)	1.25%
Goodwill	$ 751