STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2018

Stock-based compensation

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, restricted stock units, performance-based restricted stock units and the Company’s Employee Stock Purchase Program (ESPP) in the Company’s Condensed Consolidated Statements of Operations (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Cost of sales	$	16	$	39	$	30	$	75
Research and development expense		14		260		67		607
Selling, general and administrative expense		2,940		3,104		4,849		6,277
Restructuring charges		2,300		—		2,558		—
Total	$	5,270	$	3,403	$	7,504	$	6,959

Performance-based Restricted Stock Units | The 2014 Plan

Stock-based compensation

Schedule of restricted stock units

The following table summarizes the PSU activity for the six months ended June 30, 2018 under the 2014 Plan (in thousands, except per share data):

		Weighted		Weighted
		Average		Average
		Grant Date		Remaining
		Fair		Contractual		Aggregate
	Number of	Value		Term		Intrinsic
	Shares	Per Share		(in years)		Value
Non-vested performance-based restricted stock units at December 31, 2017	—	$	—
Granted	436,024		10.13
Vested	—		—
Forfeited	(36,800)		10.04
Non-vested performance-based restricted stock units at June 30, 2018	399,224	$	10.14	2.61	$	2,663