Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Assumptions used in Black-Scholes Pricing Model for New Grants

The fair value of each stock option granted is estimated on the date of grant using the Black-Scholes option-pricing model using the assumptions noted in the following table:

	Years Ended December 31,
	2015	2014	2013
Volatility	73.04%-78.7%	69.38%-77.92%	64.22%-72.65%
Expected Term (in years)	5.50-6.25	5.50-6.25	5.50-6.25
Risk-Free Interest Rates	1.54%-1.93%	1.81%-2.02%	1.01%-2.10%
Dividend Yield	—	—	—

Stock Option Activity

The following table summarizes the activity of the Plans for the year ended December 31, 2015:

	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value
Outstanding at December 31, 2014		5,817,313		$	4.45
Granted		3,159,134		$	1.11
Exercised		(165,805	)	$	1.45
Forfeited		(2,964,938	)	$	1.85
Expired		(1,049,699	)	$	5.27
Outstanding at December 31, 2015		4,796,005		$	3.78		6.93	$	596,660
Exercisable at December 31, 2015		3,153,440		$	5.09		5.86	$	325,107
Vested or expected to vest at December 31, 2015		2,276,447		$	6.56		4.61	$	115,704

Restricted Stock Activity

The following table summarizes the restricted stock activity for the year ended December 31, 2015:

	Number of Shares			Weighted- Average Price
Unvested at December 31, 2014		477,600		$	1.81
Granted		—			—
Cancelled		(201,180	)		1.87
Expired		—			—
Vested/Released		(233,670	)		1.80
Unvested at December 31, 2015		42,750		$	1.61