Note 13 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

Share-Based Payment Arrangement, Cost by Plan [Table Text Block]

	Year Ended December 31,
(in thousands)	2022		2021		2020
Stock options and other	$	16,103	$	17,553	$	13,327
Employee stock purchase plan		1,442		1,542		1,346
Total stock-based compensation expense	$	17,545	$	19,095	$	14,673
Cost of revenue	$	2,172	$	2,595	$	2,451
Operating expenses:
Marketing and sales		3,295		3,736		3,121
Research and development		2,189		2,833		2,440
General and administrative		9,889		9,931		6,661
Total stock-based compensation expense	$	17,545	$	19,095	$	14,673

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Year Ended December 31,
	2022		2021		2020
Risk-free interest rate		1.94 - 3.40%		0.80 - 1.12%		0.50 - 1.47%
Expected life (years)		6.25		6.25		6.25
Expected volatility		45.95 - 46.03%		45.28 - 45.53%		42.40 - 43.83%
Expected dividend yield		0%		0%		0%
Weighted average grant date fair value		$23.11		$128.14		$45.32

Share-Based Payment Arrangement, Option, Activity [Table Text Block]

				Weighted-
				Average
	Stock Options			Exercise Price
Options outstanding at January 1, 2020		276,266		$	72.38
Granted		60,065			105.79
Exercised		(68,958	)		57.00
Cancelled		(37,842	)		67.92
Options outstanding at December 31, 2020		229,531			86.46
Granted		57,901			128.14
Exercised		(28,991	)		58.78
Cancelled		(25,057	)		109.31
Options outstanding at December 31, 2021		233,384			97.78
Granted		118,434			48.24
Exercised		(3,114	)		30.58
Cancelled		(84,712	)		89.32
Options outstanding at December 31, 2022		263,992		$	79.07
Exercisable at December 31, 2022		102,692		$	90.22

Share-Based Payment Arrangement, Option, Exercise Price Range [Table Text Block]

	Options Outstanding, Vested and Expected to Vest			Options Exercisable
Range of Exercise Prices	Number Outstanding	Weighted Average Remaining Contractual Life	Weighted Average Exercise Price ($)	Number Exercisable	Weighted Average Exercise Price ($)
$39.11 to $66.87	137,829	7.63	49.84	32,808	56.53
$66.88 to $96.20	37,608	6.72	89.37	17,016	82.08
$96.21 to $180.46	88,555	6.81	120.17	52,868	113.74

Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]

				Weighted-
				Average
				Grant Date
	Restricted			Fair Value
	Stock Awards			Per Share
Restricted stock at January 1, 2020		314,973		$	89.55
Granted		108,179			111.76
Restrictions lapsed		(101,941	)		84.70
Forfeited		(14,012	)		94.24
Restricted stock at December 31, 2020		307,199			98.87
Granted		205,996			123.61
Restrictions lapsed		(115,908	)		91.26
Forfeited		(53,505	)		128.05
Restricted stock at December 31, 2021		343,782			111.79
Granted		315,432			42.03
Restrictions lapsed		(130,452	)		101.32
Forfeited		(50,166	)		96.48
Restricted stock at December 31, 2022		478,596		$	70.36

Schedule of Nonvested Performance-Based Units Activity [Table Text Block]

				Weighted-
				Average
				Grant Date
	Performance			Fair Value
	Stock Awards			Per Share
Performance stock at January 1, 2020		9,383		$	58.35
Granted		19,956			118.66
Restrictions lapsed		(7,113	)		58.35
Performance change		-			-
Forfeited		(2,270	)		58.35
Performance stock at December 31, 2020		19,956			118.66
Granted		15,078			203.64
Restrictions lapsed		-			-
Performance change		(10,366	)		192.95
Forfeited		(7,829	)		113.91
Performance stock at December 31, 2021		16,839			115.56
Granted		35,697			96.71
Restrictions lapsed		-			-
Performance change		(13,156	)		99.59
Forfeited		(3,578	)		121.79
Performance stock at December 31, 2022		35,802		$	77.91

Schedule of Share-based Payment Award, Awards Other Than Stock Options, Valuation Assumptions [Table Text Block]

	Year Ended December 31,
	2022	2021	2020
Risk-free interest rate	0.17 - 4.60%	0.06 - 0.17%	0.12 - 0.17%
Expected life (months)	6.00	6.00	6.00
Expected volatility	47.05 - 67.84%	53.44 - 65.53%	50.85 - 59.99%
Expected dividend yield	0%	0%	0%