Forward and Swap Contracts Level 4 (Details) (USD $)					6 Months Ended
	Sep. 30, 2012 Other Assets [Member]	Mar. 31, 2012 Other Assets [Member]	Sep. 30, 2012 Accrued Liabilities [Member]	Mar. 31, 2012 Accrued Liabilities [Member]	Sep. 30, 2012 Selling, General and Administrative Expenses [Member]	Sep. 30, 2011 Selling, General and Administrative Expenses [Member]	Sep. 30, 2012 Cost of Sales [Member]	Sep. 30, 2011 Cost of Sales [Member]	Sep. 30, 2012 Mexico, Pesos	Sep. 30, 2012 212234 Copper Ore and Nickel Ore Mining [Member]
Derivative [Line Items]
Foreign Currency Transaction Gain, before Tax					$ 115,000	$ (2,520,000)
Notional Amount of Foreign Currency Derivative Purchase Contracts									106,300,000	286,000
Derivative Assets	480,000	12,000	0	0
Derivative Liabilities	0	0	187,000	863,000
Gain (Loss) on Sale of Commodity Contracts							$ (43,000)	$ (1,576,000)