Revenue - Receivables, Right of Return Assets, Contract Liabilities, Refund Liabilities, and Warranty Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Receivables, which comprises the balance in accounts receivable, net of allowances	$ 142,804	$ 156,667
Right of return assets, which are included in prepaid expenses and other current assets	2,177	999
Refund liabilities, which are included in sales return liability	39,790	49,786
Warranty liabilities, which are included in sales return liability	4,063	4,646
Contract liabilities, which are included in accrued liabilities	39	$ 96
Contract liabilities revenue recognized	$ (69)