Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2016

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 2016 (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, 2015	2,965		$	3.89	4.35	$	442
Granted	1,474		4.19
Exercised	(212	)	2.92
Forfeited	(95	)	3.66
Expired	(235	)	8.04
Balance, December 31, 2016	3,897		$	3.81	4.58	$	3,642
Options exercisable at December 31, 2016	2,155		$	3.80	3.35	$	2,480
Options vested as of December 31, 2016 and expected to vest after December 31, 2016	3,769		$	3.80	4.53	$	3,571

Schedule of Nonvested Share Activity

The following table summarizes non-vested stock activity for 2016:

	Restricted Stock Units				Performance Stock Units
	Restricted Shares		Weighted Average Fair Value		Restricted Shares		Weighted Average Fair Value
Balance, December 31, 2015	151		$	2.51	1,625		$	2.41
Granted	97		4.93		900		4.01
Vested	(141	)	3.34		(1,658	)	2.42
Forfeited	(7	)	2.53		(30	)	3.92
Balance, December 31, 2016	100		$	3.68	837		$	4.07

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,
	2016		2015		2014
Shares issued pursuant to the ESPP	184		175		242
Cash received for the purchase of shares pursuant to the ESPP	$	417	$	322	$	514
Weighted average purchase price per share	$	2.26	$	1.84	$	2.12

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
	2016	2015	2014	2016	2015	2014
Share price	$2.27-5.30	$2.06-2.80	$2.50-3.49	$2.58-4.97	$2.15-3.00	$2.55-4.70
Expected life (in years)	4.44-4.46	4.39-4.41	4.40-4.47	1.5	1.5	1.5
Interest rate	1.09-1.58%	1.3-1.6%	1.3-1.5%	0.3-0.9%	0.1-0.5%	0.1-0.3%
Volatility	52.4-54.0%	53.5-54.6%	51.4-52.5%	42.6-46.2%	46.9-55.9%	47.3-55.6%
Dividend yield	—	—	—	—	—	—

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

For the years ended December 31, 2016, 2015 and 2014, stock-based compensation was recognized and allocated in the Consolidated Statements of Operations as follows (in thousands):

	For the Years Ended December 31,
	2016		2015		2014
Cost of sales	$	354	$	294	$	386
Research and development	845		867		818
Selling, general and administrative	2,598		2,791		2,893
Total stock-based compensation expense	$	3,797	$	3,952	$	4,097