Stock Award Plans (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Based Award Plans

The following table summarizes information about the Company’s stock-based award plans as of December 31, 2018:

	Outstanding Options		Outstanding Restricted Stock Units		Shares Available for Future Issuance
2004 Equity Incentive Plan		933,402		—		—
2013 Equity Incentive Plan		5,766,448		691,266		—
2018 Equity Incentive Plan		4,225,603		—		9,211,379
2004 Non-Employee Directors’ Stock Option Plan		50,665		—		—
Total		10,976,118		691,266		9,211,379

Stock Based Compensation Expense Recognized in Accompanying Consolidated Statements of Operations by Category

Total stock-based compensation expense recognized in the accompanying consolidated statements of operations is included in the following categories (in thousands):

	Year Ended December 31,
	2018		2017		2016
Cost of goods sold	$	379	$	460	$	695
Research and development		1,203		1,010		1,309
Selling, general and administrative		5,275		3,377		3,131
Total	$	6,857	$	4,847	$	5,135

Assumptions Used to Calculate Fair Value of Employee Stock Options

The Company calculated the fair value of employee stock options granted during the years ended December 31, 2018, 2017 and 2016 using the following assumptions:

	Year Ended December 31,
	2018		2017		2016
Risk-free interest rate	2.63% — 3.11%		1.83% — 2.13%		1.18% — 1.80%
Expected lives	5.90 — 7.19 years		5.41 — 5.78 years		5.13 — 5.82 years
Volatility	92.68% — 93.62%		83.32% — 90.39%		77.57% — 82.75%
Dividends		—		—		—

Summary of Stock Options Outstanding

The following table summarizes information about stock options outstanding:

	Number of Shares			Weighted Average Exercise Price per Share		Aggregate Intrinsic Value ($000)
Outstanding at January 1, 2018		7,089,440		$	9.33
Granted		5,158,648		$	1.94
Exercised		(6,880	)	$	1.10
Forfeited		(733,536	)		2.87
Expired		(531,554	)	$	20.56
Outstanding at December 31, 2018		10,976,118		$	5.75	$	—
Exercisable at December 31, 2018		3,672,480		$	13.03	$	—

Summary of Restricted Stock Unit Activity

A summary of restricted stock unit activity for the year ended December 31, 2018 is presented below:

	Number of Shares			Weighted Average Grant Date Fair Value per Share
Outstanding at January 1, 2018		1,135,216		$	4.08
Granted		448,600			2.02
Vested		(694,831	)		3.47
Forfeited		(197,719	)		2.84
Outstanding at December 31, 2018		691,266		$	3.71