Hedging Activities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	3 Months Ended		6 Months Ended
	Sep. 30, 2013 Designated as Hedging Instrument [Member]	Sep. 30, 2013 Designated as Hedging Instrument [Member] Fair Value, Inputs, Level 2 [Member] Canada, Dollars	Sep. 30, 2012 Designated as Hedging Instrument [Member] Fair Value, Inputs, Level 2 [Member] Canada, Dollars	Sep. 30, 2013 Designated as Hedging Instrument [Member] Fair Value, Inputs, Level 2 [Member] Canada, Dollars	Sep. 30, 2012 Designated as Hedging Instrument [Member] Fair Value, Inputs, Level 2 [Member] Canada, Dollars	Mar. 31, 2013 Designated as Hedging Instrument [Member] Fair Value, Inputs, Level 2 [Member] Canada, Dollars	Sep. 30, 2013 Not Designated as Hedging Instrument [Member] Fair Value, Inputs, Level 2 [Member] Canada, Dollars	Mar. 31, 2013 Not Designated as Hedging Instrument [Member] Fair Value, Inputs, Level 2 [Member] Canada, Dollars	Dec. 31, 2012 Not Designated as Hedging Instrument [Member] Fair Value, Inputs, Level 2 [Member] Canada, Dollars	Jun. 30, 2012 Not Designated as Hedging Instrument [Member] Fair Value, Inputs, Level 2 [Member] United Kingdom, Pounds	Sep. 30, 2013 Not Designated as Hedging Instrument [Member] Fair Value, Inputs, Level 2 [Member] Mexico, Pesos
Derivative [Line Items]
Maturity Period, Years	8 years
Notional Amount of Foreign Currency Derivatives		$ 503		$ 503		$ 503	$ 0	$ 172	$ 177	$ 151	$ 41
Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net		$ 0	$ 0	$ 0	$ 0