Allowances For Doubtful Accounts & Sales Returns (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Allowance for Doubtful Accounts [Member]
Allowances For Doubtful Accounts And Sales Returns [Line Items]
Balance at beginning of year		$ 4,642	$ 3,973	$ 3,680
Charged to costs and expenses	2,166	(383)	2,204
Reversals and write-offs	(2,405)	(579)	(1,535)
Balance at end of year	3,441	3,680	4,642
Allowance for Sales Returns [Member]
Allowances For Doubtful Accounts And Sales Returns [Line Items]
Balance at beginning of year		5,607	5,866	11,828
Charged to costs and expenses	5,111	9,965	4,971
Reversals and write-offs	(7,065)	(3,744)	(5,230)
Balance at end of year	$ 9,874	$ 11,828	$ 5,607