Share-Based Payments (Tables)

12 Months Ended

Dec. 31, 2015

Share-Based Payments

Schedule of share-based compensation recognized related to the grant of employee and non-employee stock options, SARS and non-vested stock

Share-based compensation recognized related to the grant of employee and non-employee stock options, SAR, potential Employee Stock Purchase Plan (ESPP) awards and non-vested stock was as follows, in thousands:

	Year Ended December 31,
	2015		2014		2013
Research and development	$	874	$	728	$	493
Selling, general and administrative		3,357		1,988		1,420
Total	$	4,231	$	2,716	$	1,913

Schedule of assumptions used in estimation of fair value of each award option on the date of grant using Black-Scholes option-pricing model

	Year Ended December 31,
	2015	2014	2013
Fair value of common stock	$9.13 - $21.21	$7.63 - $10.02	$5.40 - $7.90
Expected volatility	60.9% - 64.6%	64.5% - 68.3%	69.5% - 70.9%
Dividend Yield	0%	0%	0%
Expected term	6.25 years	6.25 years	6.25 - 9.60 years
Risk-free interest rate	1.54% - 1.74%	1.67% - 1.97%	1.20% - 2.94%
Expected forfeiture rate	5%	5%	5%

Summary of stock option and SAR activity

	Number of Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)
Outstanding, December 31, 2013		1,463,043		$	7.27		8.51
Granted		686,235		$	9.20
Exercised		(17,627	)	$	3.08
Forfeited		(50,902	)	$	7.79
Outstanding, December 31, 2014		2,080,749		$	7.93		8.04
Granted		971,500		$	10.12
Exercised		(205,640	)	$	4.56
Forfeited		(147,602	)	$	8.60
Outstanding, December 31, 2015		2,699,007		$	8.94		7.92
As of December 31, 2015:
Vested and expected to vest		2,654,381		$	8.93		7.90
Exercisable		901,672		$	7.95		6.86