Summary of Significant Accounting Policies - Accounts Receivable and Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Concentration Risk [Line Items]
Industry practice payment of receivables	20 days
Changes in the allowance for doubtful accounts [Roll Forward]
Balance at beginning of period	$ 141	$ 153	$ 303
Charges to costs and expenses	0	26	43
Deductions	(27)	(38)	(193)
Balance at end of period	$ 114	$ 141	$ 153
Product Concentration Risk | Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	90.00%