Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Total Stock-Based Compensation Expense

Total stock-based compensation expense was allocated to research and development, manufacturing and production and general and administrative expense as follows (in thousands):

	Year Ended December 31,
	2015		2014		2013
Research and development	$	392	$	785	$	908
Manufacturing and production		159		229		258
General and administrative		1,351		2,145		2,300
Total stock-based compensation expense	$	1,902	$	3,159	$	3,466
Cash received from RSU grants and options exercised	$	3	$	2	$	816

Summary of Stock Option Transactions under Company's Stock Incentive Plans

The following table summarizes stock option transactions under the Company’s stock incentive plans for the years ended December 31, 2015, 2014 and 2013:

	Shares			WeightedAverage Exercise Price
Outstanding December 31, 2012		7,996,569		$	3.36
Granted		2,876,382		$	2.56
Exercised		(347,450	)	$	2.34
Forfeited		(2,121,313	)	$	3.27
Outstanding December 31, 2013		8,404,188		$	3.15
Granted		1,889,614		$	1.40
Exercised		—		$	—
Forfeited		(1,699,370	)	$	3.69
Outstanding December 31, 2014		8,594,432		$	2.66
Granted		2,356,750		$	1.01
Exercised		—		$	—
Forfeited		(1,495,344	)	$	2.15
Outstanding December 31, 2015		9,455,838		$	2.33
Vested and unvested options expected to vest as of    December 31, 2015		9,235,450		$	2.35

Summary of Outstanding RSUs

A summary of the outstanding RSUs as of December 31, 2015, and changes during the year then ended is presented below:

	Shares			WeightedAverage Grant-Date Fair Value per Share
Unvested at December 31, 2014		960,066		$	1.70
Granted		788,429		$	1.04
Vested		(579,677	)	$	1.68
Cancelled		(128,076	)	$	1.37
Unvested at December 31, 2015		1,040,742		$	1.26