SCHEDULE II - Valuation & Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for Doubtful Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 125	$ 260	$ 240
Charged to Expense	94	(57)	(93)
Charged to Other Accounts	0	11	0
Deductions	548	(89)	113
Balance at End of Year	767	125	260
Inventory Valuation Reserves [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	3,144	2,383	2,643
Charged to Expense	(3,575)	229	(224)
Charged to Other Accounts	0	556	0
Deductions	5,492	(24)	(36)
Balance at End of Year	5,061	3,144	2,383
Inventory LIFO Reserves [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	32,103	28,776	29,961
Charged to Expense	2,851	3,327	(1,185)
Charged to Other Accounts	0	0	0
Deductions	0	0	0
Balance at End of Year	$ 34,954	$ 32,103	$ 28,776