Valuation And Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Valuation Account For Accounts Receivable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 1,459	$ 1,406	$ 1,950
Charged to Costs and Expenses	343	315	219
Deductions / (Recoveries)	242	262	763
Balance at End of Period	1,560	1,459	1,406
Valuation Accounts For Inventories [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	9,837	9,054	9,664
Charged to Costs and Expenses	8,762	5,470	6,661
Deductions / (Recoveries)	3,889	4,687	7,271
Balance at End of Period	$ 14,710	$ 9,837	$ 9,054