Forward and Swap Contracts (Details) In Thousands, unless otherwise specified					12 Months Ended
	Mar. 31, 2015 Other Assets USD ($)	Mar. 31, 2014 Other Assets USD ($)	Mar. 31, 2015 Accrued Liabilities USD ($)	Mar. 31, 2014 Accrued Liabilities USD ($)	Mar. 31, 2015 Selling, General and Administrative Expenses USD ($)	Mar. 31, 2014 Selling, General and Administrative Expenses USD ($)	Mar. 31, 2013 Selling, General and Administrative Expenses USD ($)	Mar. 31, 2015 Cost of Sales USD ($)	Mar. 31, 2014 Cost of Sales USD ($)	Mar. 31, 2013 Cost of Sales USD ($)	Mar. 31, 2015 Mexico, Pesos MXN	Mar. 31, 2015 Canada, Dollars CAD	Mar. 31, 2015 Euro Member Countries, Euro GBP (£)	Mar. 31, 2015 212234 Copper Ore and Nickel Ore Mining [Member] lbs
Derivative [Line Items]
Notional Amount of Foreign Currency Derivative Purchase Contracts (Deprecated 2013-01-31)											68,000	8,000	£ 2,500
Foreign Currency Transaction Gain, before Tax					(1,457)	(1,175)	161
Derivative Assets	12	167	0	0
Derivative Liabilities	0	0	616	67
Gain (Loss) on Sale of Commodity Contracts								$ (373)	$ (57)	$ (217)
Investment Contract Weight														586,500