Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Share-based Payment Arrangement [Abstract]

Schedule of non-cash stock-based compensation expense

Non-cash stock-based compensation expense (employee stock purchase plan, service-based stock options and restricted stock units) included in cost of product sales, research and development expenses and selling, general and administrative expenses is summarized in the following table: 

	Three Months Ended March 31,
(in thousands)	2021		2020
Cost of product sales	$	911	$	493
Research and development	863		513
Selling, general and administrative	5,245		2,762
Total non-cash stock-based compensation expense	$	7,019	$	3,768