Derivative Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) on Foreign Currency Derivatives Recorded in Earnings, Net	$ 36	$ 12	$ (11)
Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Foreign Currency Forward And Option Contracts Maximum Maturity Period	18 months
Not Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Foreign Currency Forward And Option Contracts Maximum Maturity Period	3 months