Goodwill and Intangible Assets (Amortization of Intangibles) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Intangible Asset Amortization Expense [Line Items]
Amortization expense related to intangible assets	$ 70	$ 67	$ 63
Amortization of Intangibles, Cost of Goods Sold [Member]
Intangible Asset Amortization Expense [Line Items]
Amortization expense related to intangible assets	(12)	(12)	(13)
Amortization of Intangibles, Depreciation and Amortization [Member]
Intangible Asset Amortization Expense [Line Items]
Amortization expense related to intangible assets	$ 58	$ 55	$ 50