Commitments and Contingent Liabilities (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2011 shipments
Commitments and Contingencies Disclosure [Abstract]
Irrevocable letters of credit outstanding	$ 6,794
Letters of credit outstanding as collateral for commodity hedges	4,000
Letters of credit outstanding for insurance reserve requirements of workers' compensation insurance carriers	1,994
Total transaction value of exports, required export license not acquired		13
Number of Shipments, required export license not acquired		5
Monetary Penalties Assessed Against The Company By OEE	$ 0