Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2017

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

Schedule of Share-based Compensation, Stock Options, Activity

The following table summarizes stock option activity for 2017 (in thousands, except average prices and weighted average remaining contractual lives):

	Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance, December 31, 2016	3,897		$	3.81	4.58	$	3,642
Granted	155		1.15
Exercised	(50	)	2.38
Forfeited	(447	)	4.16
Expired	(392	)	5.85
Balance, December 31, 2017	3,163		$	3.40	3.06	$	26
Options exercisable at December 31, 2017	2,648		$	3.48	2.59	$	4
Options vested as of December 31, 2017 and expected to vest after December 31, 2017	3,163		$	3.40	3.06	$	26

Schedule of Nonvested Share Activity

The following table summarizes non-vested stock activity for 2017:

	Restricted Stock Units				Performance Stock Units
	Restricted Shares		Weighted Average Fair Value		Restricted Shares		Weighted Average Fair Value
Balance, December 31, 2016	100		$	3.68	837		$	4.07
Granted	687		3.59		690		3.76
Vested	(150	)	3.95		(380	)	4.12
Forfeited	(209	)	3.81		(525	)	4.03
Balance, December 31, 2017	428		$	3.67	622		$	3.72

Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity

The following table summarizes shares issued under the ESPP (in thousands, except per share amounts):

	Year Ended December 31,
	2017		2016		2015
Shares issued pursuant to the ESPP	233		184		175
Cash received for the purchase of shares pursuant to the ESPP	$	398	$	417	$	322
Weighted average purchase price per share	$	1.71	$	2.26	$	1.84

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The fair value calculations for stock options and ESPP shares used the following assumptions for the years ended December 31:

	Stock Options			ESPP shares
	2017	2016	2015	2017	2016	2015
Share price	$0.83-2.50	$2.27-5.30	$2.06-2.80	$0.78-4.10	$2.58-4.97	$2.15-3.00
Expected life (in years)	4.19-4.51	4.44-4.46	4.39-4.41	1.5	1.5	1.5
Interest rate	1.8-1.9%	1.1-1.6%	1.3-1.6%	0.5-1.6%	0.3-0.9%	0.1-0.5%
Volatility	49.0-57.4%	52.4-54.0%	53.5-54.6%	31.7-105.6%	42.6-46.2%	46.9-55.9%
Dividend yield	—	—	—	—	—	—

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

For the years ended December 31, 2017, 2016 and 2015, stock-based compensation was recognized and allocated in the Consolidated Statements of Operations as follows (in thousands):

	For the Years Ended December 31,
	2017		2016		2015
Cost of sales	$	157	$	354	$	294
Research and development	387		845		867
Selling, general and administrative	1,648		2,598		2,791
Total stock-based compensation expense	$	2,192	$	3,797	$	3,952