Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 10,734		$ 6,917		$ 3,196
Cost and Expense	7,661		5,958		4,629
Other Accounts	0		0		0
Deductions	(4,836)	[1]	(2,141)	[1]	(908)	[1]
Ending Balance	13,559		10,734		6,917
Allowance for Sales Returns [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	16,046		11,901		6,143
Cost and Expense	35,771		47,916		43,284
Other Accounts	0		0		0
Deductions	(44,166)	[1]	(43,771)	[1]	(37,526)	[1]
Ending Balance	$ 7,651		$ 16,046		$ 11,901

[1] Represents write-offs of specific accounts receivable or actual returns, as applicable.