Goodwill and Intangible Assets (Amortization of Intangibles) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Intangible Asset Amortization Expense [Line Items]
Amortization expense related to intangible assets	$ (69)	$ (71)	$ (70)
Amortization of Intangibles, Cost of Goods Sold [Member]
Intangible Asset Amortization Expense [Line Items]
Amortization expense related to intangible assets	(8)	(12)	(12)
Amortization of Intangibles, Depreciation and Amortization [Member]
Intangible Asset Amortization Expense [Line Items]
Amortization expense related to intangible assets	$ (61)	$ (59)	$ (58)