Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

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

Schedule of stock option activity

	Shares		Weighted average exercise price per share		Weighted average remaining contractual life
Outstanding at December 31, 2017	6,251,589		$	9.34	6.67
Granted	472,792		19.36
Exercised	(491,654	)	3.21
Expired	—		—
Forfeited	(49,854	)	9.67
Outstanding at December 31, 2018	6,182,873		$	10.60	6.48
Exercisable at December 31, 2018	3,804,999		$	8.15	5.09
Vested and expected to vest at December 31, 2018	6,182,873		$	10.60	6.48

Schedule of allocated stock-based compensation expense

The Company recorded stock-based compensation expense in the following expense categories of its accompanying consolidated statements of operations for the years ended December 31, 2018 and 2017:

	Year Ended December 31,
	2018		2017
Cost of product sales	$	9	$	—
Research and development	$	989	1,288
Selling, general and administrative	7,545		3,808
Total stock-based compensation expense	$	8,543	$	5,096

Schedule of fair value options using Black-Scholes pricing model

The Company calculated the fair value of each option grant and the option component of the 2017 Plan on the respective dates of grant using the following weighted average assumptions:

	2010 A&R Stock Incentive Plan		2017 Employee Stock Purchase Plan
	December 31,		December 31,
	2018		2018
Risk free interest rate	2.74	%	1.53	%
Expected term (in years)	5.95		0.64
Expected volatility	74.42	%	80.40	%
Annual dividend yield	0.00	%	0.00	%

The Company calculated the fair value of each option grant and the option component of the 2017 Plan on the respective dates of grant using the following weighted average assumptions:

	2010 A&R Stock Incentive Plan		2017 Employee Stock Purchase Plan
	December 31,		December 31,
	2018		2018
Risk free interest rate	2.74	%	1.53	%
Expected term (in years)	5.95		0.64
Expected volatility	74.42	%	80.40	%
Annual dividend yield	0.00	%	0.00	%