Debt - Schedule of Debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Notes payable - current:
Uncommitted lines of credit	$ 43,062	$ 33,916
Other	729	296
Short-term Debt	43,791	34,212
Long-term debt:
Credit facility	239,000	300,000
Senior notes	225,000	300,000
Industrial development revenue bonds	11,900	11,900
Other	4,342	5,634
Long-term debt	$ 480,242	$ 617,534