CAPITAL STOCK (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Information with respect to options granted under all stock option plans for the year ended December 31, 2020 was as follows:


	Total Number of Options	Weighted- Average Exercise Price	Weighted- Average Remaining Contractual Life (years)	Aggregate Intrinsic Value (in thousands)
Options Outstanding at December 31, 2017	2,290,017	$9.65	2.31	—
Granted	—	—
Exercised	—	—
Forfeited or Expired	(1,398,125)	10.42
Options Outstanding at December 31, 2018	891,892	$8.46	1.55	—
Granted	—	—
Exercised	(70,006)	7.39
Forfeited or Expired	(256,886)	10.70
Options outstanding at December 31, 2019	565,000	$7.57	1.17	$	571
Granted	—	—
Exercised	(319,000)	7.65
Forfeited or Expired	—	—
Options outstanding at December 31, 2020	246,000	$7.48	0.44	$	1,358

Exercisable at:
December 31, 2018	891,892	$8.46	1.55	$—
December 31, 2019	565,000	$7.57	1.17	$571
December 31, 2020	246,000	$7.48	0.44	$1,358

Non-vested restricted stock and restricted stock units

Information with respect to non-vested time-based restricted stock units for the year ended December 31, 2020 was as follows:


	Number of Restricted Stock Units	Weighted- Average Grant-Date Fair Value	Shares Retained to Cover Statutory Minimum Withholding Taxes
Outstanding at December 31, 2017	1,809,138	$5.49
Granted	1,783,728	5.08
Vested	(688,106)	5.61	213,531
Forfeited	(926,084)	5.42
Outstanding at December 31, 2018	1,978,676	$5.12
Granted	1,320,536	7.33
Vested	(991,819)	5.16	307,005
Forfeited	(219,460)	5.98
Outstanding at December 31, 2019	2,087,933	$6.41
Granted	1,518,714	7.20
Vested	(1,193,553)	6.33	403,798
Forfeited	(298,215)	6.52
Outstanding at December 31, 2020	2,114,879	7.01

Employee stock purchase plan

The following table sets forth the weighted-average key assumptions and fair value results for shares issued under the ESPP during the years ended December 31, 2020, 2019, and 2018:


	Year Ended December 31,
	2020	2019	2018
Expected dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate	0.82%	2.37%	1.85%
Expected volatility	72.1%	48.6%	55.3%
Expected life (in years)	0.50	0.49	0.50
Weighted-average fair value of shares issued (per share)	$1.40	$1.04	$0.94

The following table sets forth the quantities and average prices of shares issued under the ESPP for the years ended December 31, 2020, 2019, and 2018:


	Year Ended December 31,
	2020	2019	2018
Shares issued under the ESPP	61,750	69,179	117,653
Average price of shares issued	$8.67	$7.48	$4.22

Allocated share-based compensation expense

Stock-based compensation was included in the following captions in our consolidated statements of operations for the years ended December 31, 2020, 2019, and 2018, respectively (in thousands):


	Year Ended December 31,
	2020		2019		2018
Share-based compensation expense by type:
Stock Options	$	—	$	—	$	—
Time-based Restricted Stock Units	8,340		5,900		4,011
Performance-based Restricted Stock Units	2,211		1,964		2,146
ESPP	113		94		101
Total Share-based compensation expense	$	10,664	$	7,958	$	6,258


	Year Ended December 31,
	2020		2019		2018
Cost of products revenues	$	513	$	343	$	128
Cost of service revenues	826		274		194
Research and development expenses	1,725		1,068		667
Marketing and selling expenses	2,176		1,797		1,540
General and administrative expenses	5,424		4,476		3,729
Total	$	10,664	$	7,958	$	6,258