Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

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	2016	2015	2014
Expected dividend rate	—%	—%	—%
Expected stock price volatility	78.7 – 92.2%	77.4 – 88.1%	82.4 – 88.2%
Risk-free interest rate	1.1 – 2.1%	1.5 – 2.0%	1.7 – 2.2%
Expected life (years)	5.5 – 6.3	5.5 – 6.3	5.5 – 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, 2014	477,530		$	21.74	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		$	36.43	8.7	$	5,000
Granted	1,110,530		$	3.01
Exercised	(39,231	)	$	3.06
Expired	(85,700	)	$	35.76
Forfeited	(153,307	)	$	3.61
Outstanding at December 31, 2016	3,355,692		$	4.66	8.2	$	610
Exercisable at December 31, 2016	1,339,675		$	6.99		$	106