Financing Arrangement (Schedule Of Interest Expense Related To Notes) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Debt Instruments [Abstract]
Loss on conversion of senior notes	$ (2)	$ 0	$ (8)	$ 0
Amortization of debt discount	(3)	(5)	(14)	(16)
Amortization of debt issuance costs	(1)	0	(2)	(2)
Coupon interest expense	(1)	(2)	(3)	(4)
Interest Expense, Other	0	(1)	0	(2)
Total interest expense	$ (7)	$ (8)	$ (27)	$ (24)