Debt - Schedule of Debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Notes payable - current:
Uncommitted lines of credit	$ 33,916	$ 21,572
Other	296	150
Short-term Debt	34,212	21,722
Long-term debt:
Credit facility	300,000	291,000
Senior notes	300,000	300,000
Industrial development revenue bonds	11,900	11,900
Other	5,634	3,254
Long-term debt	$ 617,534	$ 606,154