Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of weighted average assumptions used to estimate fair value of each service-based stock option grant

The fair value of each service-based stock option grant for the reported periods is estimated on the date of the grant using the Black-Scholes option-pricing model using the weighted average assumptions noted in the following table.

	Year Ended December 31,
Service-Based Stock Options	2015	2014	2013
Expected dividend rate	—%	—%	—%
Expected stock price volatility	77.4 – 88.1%	82.4 – 88.2%	74.0 – 87.9%
Risk-free interest rate	1.5 – 2.0%	1.7 – 2.2%	0.1 – 2.1%
Expected life (years)	5.5 – 6.3	5.5 – 6.3	5.0 – 6.3

Summary of activity for service-based stock options

The following table summarizes the activity for service-based stock options for the indicated periods: 

Service-Based Stock Options	Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding at December 31, 2012	499,374		$	47.60	7.5	$	—
Granted	75,751		$	21.32
Exercised	—		$	—		$	—
Expired	(164,189	)	$	51.76
Forfeited	(113,076	)	$	45.38
Outstanding at December 31, 2013	297,860		$	39.53	7.9	$	—
Granted	242,029		$	3.91
Exercised	—		$	—		$	—
Expired	(32,012	)	$	42.63
Forfeited	(30,347	)	$	32.13
Outstanding at December 31, 2014	477,530		$	36.43	8.0	$	—
Granted	2,216,600		$	3.11
Exercised	(3,566	)	$	3.02		$	1,000
Expired	(17,791	)	$	40.02
Forfeited	(149,373	)	$	3.35
Outstanding at December 31, 2015	2,523,400		$	6.36	8.7	$	5,000
Exercisable at December 31, 2015	661,229		$	14.27	7.9	$	—