Stock-Based Compensation - Compensation Expense (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee and non-employee stock options
Stock based compensation expense
Options granted (in shares)	1,838
Stock-based compensation expense	$ 28,624	$ 14,198	$ 11,402
Unrecognized compensation expense	50,200
Employee and non-employee stock options | Cost of product revenues
Stock based compensation expense
Stock-based compensation expense	937	569	544
Employee and non-employee stock options | Research and development
Stock based compensation expense
Stock-based compensation expense	5,354	4,043	3,214
Employee and non-employee stock options | Selling, general and administrative
Stock based compensation expense
Stock-based compensation expense	22,333	9,586	7,644
Employee stock options
Stock based compensation expense
Stock-based compensation expense	27,989	14,081	11,402
Employee stock options | Cost of product revenues
Stock based compensation expense
Stock-based compensation expense	905	564	544
Employee stock options | Research and development
Stock based compensation expense
Stock-based compensation expense	5,354	4,043	3,214
Employee stock options | Selling, general and administrative
Stock based compensation expense
Stock-based compensation expense	21,730	9,474	$ 7,644
Non-employee stock options
Stock based compensation expense
Stock-based compensation expense	$ 635	117
Unrecognized compensation expense, weighted average period of recognition	2 years 10 months 9 days
Non-employee stock options | Cost of product revenues
Stock based compensation expense
Stock-based compensation expense	$ 32	5
Non-employee stock options | Selling, general and administrative
Stock based compensation expense
Stock-based compensation expense	$ 603	$ 112