Valuation And Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance For Uncollectible Accounts Receivable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 2,153	$ 1,327	$ 2,085
Costs Charged to Expense	1,544	1,348	992
Deductions and Write-offs	(1,175)	(522)	(1,750)
Balance at End of Period	2,522	2,153	1,327
Allowance For Sales Returns [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	5,369	9,006	8,704
Costs Charged to Expense	(946)	(3,637)	302
Balance at End of Period	$ 4,423	$ 5,369	$ 9,006