Goodwill and Intangible Assets, Net - Narrative - Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2019
Goodwill [Line Items]
Amortization expense of intangible assets	$ 112	$ 122
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Estimated annual amortization expense, remainder of 2020	298
Estimated annual amortization expense, 2021	389
Estimated annual amortization expense, 2022	365
Estimated annual amortization expense, 2023	277
Estimated annual amortization expense, 2024	248
Estimated annual amortization expense, thereafter	2,023
European Pharmaceutical Solutions
Goodwill [Line Items]
Accumulated goodwill impairment losses	2,913		$ 2,943
Other
Goodwill [Line Items]
Accumulated goodwill impairment losses	$ 470		$ 461