Goodwill and Intangible Assets, Net - Narrative - Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense of intangible assets	$ 115	$ 109	$ 230	$ 221
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Estimated annual amortization expense, remainder of 2017	181		181
Estimated annual amortization expense, 2018	369		369
Estimated annual amortization expense, 2019	350		350
Estimated annual amortization expense, 2020	325		325
Estimated annual amortization expense, 2021	298		298
Estimated annual amortization expense, thereafter	$ 1,538		$ 1,538