Stock-Based Compensation - Schedule of non-cash stock-based compensation expense (Details) - Employee stock purchase plan and service-based stock options - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	$ 2,675	$ 3,285	$ 10,819	$ 10,095
Cost of goods sold
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	481	543	1,541	1,519
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	458	583	1,455	1,993
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	$ 1,736	$ 2,159	$ 7,823	$ 6,583