Debt (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Notes payable - current:
Uncommitted lines of credit	$ 64,412	$ 33,916
Other	639	296
Short-term Debt	65,051	34,212
Long-term debt:
Credit facility	375,000	300,000
Senior notes	225,000	300,000
Industrial development revenue bonds	11,900	11,900
Other	4,961	5,634
Long-term debt	$ 616,861	$ 617,534