Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Assumptions Used to Calculate Fair Value of Options Granted to Employees

The fair value of stock options granted to employees during the three and nine months ended September 30, 2016 and 2015 was estimated at the date of grant using the following assumptions:

	Three Months Ended September 30,		Nine Months Ended September 30,
	2016	2015	2016	2015
Risk-free interest rate	1.1 – 1.4%	1.7 – 1.9%	1.1 – 1.5%	1.5 – 1.8%
Expected dividend yield	0%	0%	0%	0%
Expected term	5.8 years	5.8 – 5.9 years	5.0 – 5.8 years	5.0 – 5.9 years
Expected volatility	67%	67%	67 – 69%	66 – 67%

Schedule of Recognized Stock-Based Compensation Expense

The Company recognized stock-based compensation expense during the three and nine months ended September 30, 2016 and 2015 as follows:

	Three Months Ended September 30,					Nine Months Ended September 30,
(in thousands)	2016			2015		2016			2015
Employee awards:
Research and development expense	$	1,596		$	2,116	$	5,268		$	6,451
Selling, general and administrative expense		1,663			1,565		6,100			5,519
Stock-based compensation expense for    employee awards		3,259			3,681		11,368			11,970
Stock-based compensation expense for    non-employee awards		—			9		1			57
Less: stock-based compensation expense   capitalized to inventory		(88	)		—		(308	)		—
Total stock-based compensation expense	$	3,171		$	3,690	$	11,061		$	12,027

Summary of Stock Option Activity

The following table summarizes stock option activity during the nine months ended September 30, 2016:

						Weighted-Average Remaining		Aggregate
(in thousands, except per share amounts)	Options			Weighted-Average Exercise Price		Contractual Term (in years)		Intrinsic Value
Outstanding at December 31, 2015		19,211		$	5.72		6.24	$	47,963
Granted		4,189		$	5.57
Exercised		(1,196	)	$	3.37
Forfeited		(1,204	)	$	6.89
Outstanding at September 30, 2016		21,000		$	5.76		6.01	$	26,505
Vested and expected to vest at September 30, 2016		20,658		$	5.75		5.96	$	26,271
Exercisable at September 30, 2016		15,691		$	5.40		5.14	$	23,323