Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation Expense

	Year Ended December 31,
	2019		2018		2017
	(In thousands)
Research and development	$	6,095	$	4,961	$	5,240
Selling, general and administrative		7,690		6,752		7,448
Total	$	13,785	$	11,713	$	12,688

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

	Year Ended December 31,
	2019			2018			2017
Estimated weighted-average fair value	$	9.93		$	10.32		$	8.66
Weighted-average assumptions:
Expected volatility		80	%		78	%		74	%
Expected term, in years		6.0			6.0			6.0
Risk-free interest rate		2.41	%		2.68	%		2.05	%
Expected dividend yield		—	%		—	%		—	%

Schedule of Stock Option Activity

		Weighted-
		Average			Aggregate
		Exercise		Remaining	Intrinsic
	Options	Price per		Contractual Life	Value
	Outstanding	Share		(In years)	(In thousands)
Balance at December 31, 2018	10,313,138	$	11.22
Granted	2,098,705		14.23
Exercised	(799,815)		9.50
Forfeited	(404,097)		16.28
Balance at December 31, 2019	11,207,931	$	11.72	6.0	$	31,912
Vested and expected to vest at December 31, 2019	10,876,043	$	11.65	6.0	$	31,661
Exercisable at December 31, 2019	8,212,177	$	10.87	5.1	$	29,546