Description Of Business And Summary Of Significant Accounting Policies (Foreign Currency Translation) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Derivative [Line Items]
Foreign Currency Transaction Gain (Loss), Realized	$ (40)	$ (14)	$ (62)
Net gain (loss) on foreign currency forward contracts	$ 46	$ 15	$ 59