Debt (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Notes payable - current:
Uncommitted lines of credit	$ 26,103	$ 33,916
Other	670	296
Short-term Debt	26,773	34,212
Long-term debt:
Credit facility	320,007	300,000
Senior notes	225,000	300,000
Industrial development revenue bonds	11,900	11,900
Other	4,688	5,634
Long-term debt	$ 561,595	$ 617,534