Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2016

Employee Benefit Plans

Assumptions made for the purpose of estimating fair value

	2016	2015	2014
Expected term of options (years)	6	6	6
Risk free interest rate	1.27% - 1.69%	1.52% - 1.87%	1.77% - 1.94%
Volatility	103.87% - 104.88%	104.03% - 105.29%	107.17% - 113.92%

Schedule of Share-based Compensation, Stock Options, Activity

A summary of stock option activity for the year December 31, 2016 is as follows (in thousands except share amounts):

				Weighted
		Weighted		Average
		Average		Remaining	Aggregate
		Exercise		Contractual	Intrinsic
	Shares	Price		Terms	Value
Options outstanding at December 31, 2015	11,700,786	$	3.29	8.3
Granted	3,702,500		1.72
Exercised	(274,000)		0.37
Forfeited	(347,482)		2.91
Expired	(21,750)		49.18
Options outstanding at December 31, 2016	14,760,054	$	2.90	7.9	$	878
Options exercisable at December 31, 2016	7,368,564		3.28	7.0		878
Options unvested at December 31, 2016	7,391,490	$	2.52	8.9		—

Nonvested Restricted Stock Shares Activity

A summary of restricted stock activity for the year ended December 31, 2016 is as follows (in thousands except share amounts):

		Aggregate
		Intrinsic
	Shares	Value
Unvested restricted stock at December 31, 2015	204,444
Vested	(191,111)
Unvested restricted stock at December 31, 2016	13,333	$	16