Schedule II - Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Valuation and Qualifying Accounts [Roll Forward]
Balance Beginning of Year	$ 1,467	$ 1,364	$ 1,894
Charged to Costs and Expenses	6,652	5,138	5,008
Write-offs, Net of Recoveries and Actual Returns	(6,441)	(5,035)	(5,538)
Balance at End of Year	1,678	1,467	1,364
Allowance for doubtful accounts
Valuation and Qualifying Accounts [Roll Forward]
Balance Beginning of Year	898	727	972
Charged to Costs and Expenses	446	616	467
Write-offs, Net of Recoveries and Actual Returns	(408)	(445)	(712)
Balance at End of Year	936	898	727
Allowance for returns
Valuation and Qualifying Accounts [Roll Forward]
Balance Beginning of Year	569	637	922
Charged to Costs and Expenses	6,206	4,522	4,541
Write-offs, Net of Recoveries and Actual Returns	(6,033)	(4,590)	(4,826)
Balance at End of Year	$ 742	$ 569	$ 637