Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Information Regarding Stock Options Outstanding Stock Options Vested and Expected to Vest and Stock Options Exercisable

Information regarding the Company’s stock options outstanding, stock options vested and expected to vest, and stock options exercisable at December 31, 2016, was as follows (in thousands except weighted average exercise price and contractual term):

	NumberofShares		WeightedAverage ExercisePrice		Weighted Average Remaining Contractual Term (Years)		AggregateIntrinsic Value
Balances at December 31, 2016
Stock options outstanding		15,787	$	4.39		6.3	$	8,696
Stock options vested and expected to vest		15,541		4.38		6.2		8,695
Stock options exercisable		10,600		4.03		5.3		8,557

Recognition of Stock-Based Compensation Expense

Stock-based compensation expense recognized on the Company’s consolidated statements of operations for the years ended December 31, 2016, 2015 and 2014, was as follows (in thousands):

	Year Ended December 31,
	2016		2015		2014
Stock-based compensation expense by caption:
Research and development	$	1,091	$	1,260	$	998
Selling, general and administrative		6,974		5,470		4,155
Total stock-based compensation expense	$	8,065	$	6,730	$	5,153

Weighted Average Assumptions Used to Value Stock-Based Awards

The weighted average assumptions used to value the Company’s stock-based awards for the years ended December 31, 2016, 2015 and 2014, was as follows:

	Year Ended December 31,
	2016		2015		2014
Stock Options:
Expected term (in years)		5.85		5.66		5.71
Estimated volatility		49%		56%		61%
Risk-free interest rate		1.41%		1.55%		1.73%
Expected dividend yield		0%		0%		0%
Employee Stock Purchase Plan Rights:
Expected term (in years)		0.76		0.75		0.76
Estimated volatility		47%		53%		52%
Risk-free interest rate		0.55%		0.28%		0.10%
Expected dividend yield		0%		0%		0%

2008 Equity Incentive Plan

Activity Under Equity Incentive Plans Related to Stock Options

Activity under the Company’s equity incentive plans related to stock options is set forth below (in thousands except weighted average exercise price):

	Number of Options Outstanding			Weighted Average Exercise Price per Share
Balances at December 31, 2015		14,119		$	4.21
Granted		2,722			5.39
Forfeited		(287	)		4.93
Expired		(128	)		9.18
Exercised		(639	)		3.45
Balances at December 31, 2016		15,787			4.39

Activity Under Equity Incentive Plans Related to RSUs

Activity under the Company’s equity incentive plans related to RSUs is set forth below (in thousands except per share amounts):

	Number of Shares Outstanding			Weighted Average Grant Date Fair Value per Share
Balances at December 31, 2015		—		$	—
Granted		762			5.26
Forfeited		(23	)		5.06
Vested		—			—
Balances at December 31, 2016		739			5.26