Share Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Stock Based Compensation

Summary of stock option activity

The following is a summary of option activity under the Plan (in thousands, except share and per share amounts):

				Weighted-Average
		Weighted-Average		Remaining
	Number of	Exercise Price Per		Contractual Term	Aggregate Intrinsic
	Shares	Share		(In years)	Value
Outstanding at December 31, 2015	3,484,298	$	8.79	7.64	$	14,620
Granted	1,489,384		8.35
Exercised	(165,803)		2.84			930
Forfeited	(664,303)		11.55
Canceled	(100,949)		17.38
Outstanding at December 31, 2016	4,042,627		8.20	7.05		4,091
Exercisable at December 31, 2016	2,251,925		6.77	5.61		3,922
Vested or expected to vest at December 31, 2016	3,845,455		8.12	6.95		4,084

Schedule of estimated assumptions used to calculate weighted-average fair value of options granted

	Year ended
	December 31,
	2016		2015
Weighted-average risk-free interest rate	1.42	%	1.69	%
Expected dividend yield	0.00	%	0.00	%
Expected volatility	61	%	56	%
Expected terms	6.0	years	6.0	years

Summary of restricted stock unit activity

The following is a summary of restricted stock unit activity under the Plan (in thousands, except share and per share amounts):

		Weighted-Average
	Number of	Grant Date Fair
	Shares	Value
Nonvested at December 31, 2015	—	$	—
Granted	272,195		5.83
Exercised	—		—
Forfeited	—		—
Canceled	—		—
Nonvested at December 31, 2016	272,195		5.83

Schedule of estimated assumptions used to calculate weighted-average fair value of the purchase rights granted

	Year ended
	December 31,
	2016		2015
Weighted-average risk-free interest rate	0.50	%	0.19	%
Expected dividend yield	0.00	%	0.00	%
Expected volatility	67	%	57	%
Expected terms	0.5	years	0.5	years

Summary of stock-based compensation expense for stock options granted that was recorded in the Company's results of operations

The following table summarizes the stock-based compensation expense for stock options granted to employees and non-employees, as well as stock-compensation expense for the 2014 ESPP that was recorded in the Company’s results of operations for the years presented (in thousands):

	Year ended
	December 31,
	2016		2015		2014
Cost of product revenue	$	123	$	—	$	—
Research and development		1,127		1,213		501
Selling, general and administrative		3,480		2,840		1,152
Total stock-based compensation expense	$	4,730	$	4,053	$	1,653