Revenue Recognition - Sales Return Reserve (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 43,986	$ 34,314
Provision	35,890	35,636
Sales returns	(19,092)	(18,958)
Ending balance	$ 60,784	$ 50,992