STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2021

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

For 2021, 2020, and 2019, the fair value of each option grant was estimated using the Black-Scholes option-pricing model, using the following assumptions:

	Years Ended December 31,
	2021	2020	2019
Expected option life (years)	5.50 - 6.25	5.50 - 6.25	5.50 - 6.25
Risk-free interest rate	0.68% - 1.39%	0.31% - 1.63%	1.91% - 2.58%
Expected stock price volatility	48.2% - 49.5%	49.2% - 51.2%	63.1% - 66.7%
Dividend yield	—	—	—

Summary of Stock option and restricted stock activity

A summary of stock option activity under the 2008 Plan and Inducement Grants during the years ended December 31, 2021, 2020, and 2019 is presented below:

				Weighted		Weighted
				Average		Average
		Weighted		Grant-		Remaining
(in thousands, except per share and	Option	Average		date		Term	Aggregate
remaining term data)	Shares	Exercise Price		Fair Value		(years)	Intrinsic Value
Outstanding December 31, 2018	759	$	49.74			7.6	$	2,221
Granted	160		65.97	$	40.14
Exercised	(130)		41.99					3,335
Forfeited	(31)		56.66
Expired	(1)		54.36
Outstanding December 31, 2019	757	$	54.21			7.2	$	6,761
Granted	231		30.29	$	14.39
Exercised	(8)		36.81					216
Forfeited	(44)		54.54
Expired	—		—
Outstanding at December 31, 2020	936	$	48.44			7.1	$	372
Granted	168		33.09	$	15.71
Exercised	(42)		40.25					552
Forfeited	(19)		59.84
Expired	(55)		55.59
Outstanding at December 31, 2021	988	$	45.56			6.6	$	6,786
Exercisable at December 31, 2021	613	$	51.60			5.3	$	1,994

Non-vested Restricted Stock Shares Activity

A summary of RSA activity under the Plan during the years ended December 31, 2021, 2020, and 2019 is presented below:

		Weighted
		Average Grant		Weighted Average
(in thousands, except per share and		Date Fair		Remaining Term
remaining term data)	Shares	Value		(years)
Unvested at December 31, 2018	117	$	54.04	2.1
Granted	122		66.39
Vested	(42)		54.77
Forfeited	(5)		62.63
Unvested at December 31, 2019	192	$	61.46	2.6
Granted	305		44.42
Vested	(127)		58.88
Forfeited	(18)		51.53
Unvested at December 31, 2020	352	$	48.14	2.7
Granted	541		33.02
Vested	(125)		48.32
Forfeited	(61)		48.16
Unvested at December 31, 2021	707	$	36.52	2.8

Employee Stock Purchase Plan 2016 [Member]

Summary of allocated expense

(in thousands)	Years Ended December 31,
	2021		2020		2019
Cost of sales	$	15	$	21	$	18
Research and development		21		36		29
Selling, general, and administrative		87		123		100
	$	123	$	180	$	147

Stock Incentive Plan 2008 [Member]

Summary of allocated expense

	Years Ended December 31,
(in thousands)	2021		2020		2019
Cost of sales	$	5	$	115	$	101
Research and development		543		561		756
Selling, general, and administrative		9,818		12,080		8,213
	$	10,366	$	12,756	$	9,070