Forward and Swap Contracts Level 4 (Details) In Thousands, unless otherwise specified					3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Dec. 31, 2013 Other Assets [Member] USD ($)	Mar. 31, 2013 Other Assets [Member] USD ($)	Dec. 31, 2013 Accrued Liabilities [Member] USD ($)	Mar. 31, 2013 Accrued Liabilities [Member] USD ($)	Dec. 31, 2013 Selling, General and Administrative Expenses [Member] USD ($)	Dec. 31, 2012 Selling, General and Administrative Expenses [Member] USD ($)	Dec. 31, 2013 Selling, General and Administrative Expenses [Member] USD ($)	Dec. 31, 2012 Selling, General and Administrative Expenses [Member] USD ($)	Dec. 31, 2013 Cost of Sales [Member] USD ($)	Dec. 31, 2012 Cost of Sales [Member] USD ($)	Dec. 31, 2013 Cost of Sales [Member] USD ($)	Dec. 31, 2012 Cost of Sales [Member] USD ($)	Dec. 31, 2013 Mexico, Pesos MXN	Dec. 31, 2013 Canada, Dollars CAD	Dec. 31, 2013 212234 Copper Ore and Nickel Ore Mining [Member] CHF
Derivative [Line Items]
Foreign Currency Transaction Gain, before Tax					$ (271)	$ (90)	$ (842)	$ 24
Notional Amount of Foreign Currency Derivative Purchase Contracts													114,700	15,000
Derivative Assets	0	161	0	0
Derivative Liabilities	0	0	388	128
Gain (Loss) on Sale of Commodity Contracts									0	(169)	(57)	(211)
Notional Amount of Foreign Currency Derivative Sale Contracts													24,700		3,500