Note 10 - Common Stock and Stock-based Compensation Plans (Tables)

9 Months Ended

Sep. 30, 2020

Notes Tables

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

	Number of options and SAR units (1)			Weighted average exercise price		Weighted average remaining contractual term		Aggregate intrinsic- value
Outstanding as of December 31, 2019		642,253		$	20.14		3.5	$	4,718
Granted		—			—
Exercised		(333,980	)		18.42
Forfeited or expired		(21	)		16.20
Outstanding as of September 30, 2020 (2)		308,252		$	22.02		3.7	$	5,349
Exercisable as of September 30, 2020 (3)		298,752		$	21.74		3.6	$	5,266

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

	Number of RSUs and PSUs			Weighted Average Grant-Date Fair Value
Unvested as of December 31, 2019		732,564		$	30.11
Granted		466,921			29.17
Vested		(301,792	)		31.33
Forfeited or expired		(43,295	)		29.82
Unvested as of September 30, 2020		854,398		$	29.18

Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Nine months ended September 30,				Three months ended September 30,
	2020 (unaudited)		2019 (unaudited)		2020 (unaudited)		2019 (unaudited)
Cost of revenue	$	473	$	464	$	159	$	168
Research and development, net		5,115		4,314		1,770		1,494
Sales and marketing		1,496		1,112		533		362
General and administrative		2,986		1,957		1,084		728
Total equity-based compensation expense	$	10,070	$	7,847	$	3,546	$	2,752

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]

	Nine months ended September 30,						Three months ended September 30,
	2020 (unaudited)			2019 (unaudited)			2020 (unaudited)			2019 (unaudited)
Expected dividend yield		0%			0%			0%			0	%
Expected volatility	32%	-	60%	42%	-	43%	37%	-	60%		42	%
Risk-free interest rate	0.1%	-	1.9%	2.0%	-	2.5%	0.1%	-	1.8%		2.0	%
Contractual term of up to (months)		24			24			24			24