Long-Term Debt and Credit Agreements - Schedule of long term debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term debt	$ 92,814	$ 74,030
Less current portion	0	(305)
Long-term debt, less current portion	92,814	73,725
Credit Agreement [Member]
Debt Instrument [Line Items]
Long-term debt	57,814	37,800
Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt	35,000	35,000
Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Long-term debt	$ 0	$ 1,230