Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	$ 3,016	$ 1,984	$ 8,547	$ 6,092
Stock options
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	693	619	2,040	1,735
Compensation not yet recognized, stock options	4,400		4,400
RSUs and RSAs
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	742	603	1,974	1,812
Compensation not yet recognized, share-based awards other than options	4,000		4,000
PSUs
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	640	295	1,683	922
Compensation not yet recognized, share-based awards other than options	1,500		1,500
PBOs
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	941	467	2,850	1,623
Compensation not yet recognized, share-based awards other than options	2,600		2,600
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	652	385	1,726	1,279
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	$ 2,364	$ 1,599	$ 6,821	$ 4,813