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
	Mar. 31, 2020	Mar. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	$ 3,768	$ 2,628
Cost of goods sold
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	493	260
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	513	525
General, selling and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total non-cash stock-based compensation expense	$ 2,762	$ 1,843