Derivative Financial Instruments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivative [Line Items]
Maturity period, maximum (in months)	12 months
Cash Flow Hedging [Member]
Derivative [Line Items]
Notional value of foreign currency purchase contracts	$ 84	$ 74
Notional value of foreign currency sale contracts	149	78
Foreign currency option contracts outstanding total fair value	6	2
Net impact of gains and losses on foreign currency option contracts	5
Balance Sheet Hedging [Member]
Derivative [Line Items]
Notional value of foreign currency foward contracts	306	242
Nondesignated [Member] | United States Dollar [Member] | Balance Sheet Hedging [Member]
Derivative [Line Items]
Notional value of foreign currency purchase contracts	87	37
Notional value of foreign currency sale contracts	213	197
Nondesignated [Member] | British Pounds Sterling [Member] | Balance Sheet Hedging [Member]
Derivative [Line Items]
Notional value of foreign currency sale contracts	$ 6	$ 8