Description of Business and Summary of Significant Accounting Policies - Advertising (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Capitalized Direct Response Advertising Costs [Line Items]
Advertising expense		$ 4,800	$ 9,700	$ 7,500
ASC 340-40
Capitalized Direct Response Advertising Costs [Line Items]
Advertising expense				$ (522)
New accounting pronouncement or change in account principle, effect of amortization period adjustment to production costs	$ 1,900