Schedule of Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts and Customer Credits, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Allowance for Doubtful Accounts and Customer Credits
Movement in Valuation Allowances and Reserves
Beginning Balance	$ 4,236	$ 3,420	$ 2,846
Additions Charged to Net Revenues and Costs and Expenses	8,167	9,411	9,063
Write-offs of Accounts Receivable and Credit Memos Paid	(8,512)	(8,595)	(8,489)
Ending Balance	$ 3,891	$ 4,236	$ 3,420