Goodwill And Acquisition-Related Intangibles, Net (Schedule Of Future Amortization Of Acquisition-Related Intangibles) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Mar. 31, 2017	[1]
Finite-Lived Intangible Assets
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	$ 5
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	13
Finite-Lived Intangible Assets, Amortization Expense, Year Two	6
Finite-Lived Intangible Assets, Amortization Expense, Year Three	6
Finite-Lived Intangible Assets, Amortization Expense, Year Four	6
Finite-Lived Intangible Assets, Amortization Expense, Year Five	6
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	15
Finite-Lived Intangible Assets, Net	81	$ 8
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year through after Year Five [Member]
Finite-Lived Intangible Assets
Finite-Lived Intangible Assets, Net	$ 57

[1] Derived from audited Consolidated Financial Statements.