STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2015

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

Summary of Black-Scholes Valuation Model used to Determine Fair Value of Stock Options

The Black-Scholes model requires the input of highly subjective assumptions, which are summarized in the table below for the years ended December 31:

	2015	2014	2013
Expected dividend yield	—	—	—
Expected stock price volatility	66%	67%	83%
Risk-free interest rate	1.2%	1.3%	0.9%
Expected life of options in years	4.0	4.0	4.4

Schedule of Stock-based Compensation

Our stock-based compensation for the years ended December 31 was as follows (in thousands):

	2015		2014		2013
Stock-based compensation by type of award:
Stock options	$	1,018	$	994	$	1,289
Restricted stock units	1,227		484		124
Employee stock purchase plan	35		48		20
	$	2,280	$	1,526	$	1,433
Stock-based compensation by category of expense:
Cost of goods sold	$	167	$	40	$	52
Research, development and engineering	253		181		254
Selling, general and administrative	1,860		1,305		1,127
	$	2,280	$	1,526	$	1,433