STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2019

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

Schedule of stock-based compensation expense recognized for stock options, stock awards, restricted stock units and the Company's employee stock purchase program (ESPP)

The following table presents stock-based compensation expense recognized for stock options, stock awards, RSUs, PSUs and the Company’s ESPP in the Company’s Condensed Consolidated Statements of Operations (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Cost of sales	$	50	$	16	$	50	$	30
Research and development expense	76		14		349		67
Selling, general and administrative expense	2,508		2,940		4,937		4,849
Restructuring	—		2,300		—		2,558
Total	$	2,634	$	5,270	$	5,336	$	7,504