Schedule II Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 0
Additions charged to Expense or Revenue	719
Deductions and write-offs	18
Balance at End of Year	737	$ 0
Allowance for product returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	4,115	8,510	$ 7,362
Additions charged to Expense or Revenue	705	0	1,148
Deductions and write-offs	(2,499)	(4,395)	0
Balance at End of Year	2,321	4,115	8,510
Allowance for obsolescence
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	719	589	768
Additions charged to Expense or Revenue	340	1,204	511
Deductions and write-offs	(220)	(1,074)	(690)
Balance at End of Year	$ 839	$ 719	$ 589