(Schedule Of Amortization Of Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 9	$ 6	$ 7
Cost of product
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	2	27	14
Cost of service and other
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	0	16	33
Operating expenses
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	9	6	7
Total amortization
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 11	$ 49	$ 54