Debt (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Notes payable - current:
Uncommitted lines of credit	$ 61,538	$ 21,572
Other	179	150
Short-term Debt	61,717	21,722
Long-term debt:
Credit facility	315,000	291,000
Senior notes	300,000	300,000
Industrial development revenue bonds	11,900	11,900
Other	3,137	3,254
Long-term debt	$ 630,037	$ 606,154