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

6 Months Ended

Jun. 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		(201,066	)		17.36
Forfeited or expired		(21	)		16.20
Outstanding as of June 30, 2020 (2)		441,166		$	21.42		3.4	$	7,061
Exercisable as of June 30, 2020 (3)		415,166		$	20.98		3.3	$	6,827

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		409,437			27.65
Vested		(238,614	)		32.19
Forfeited or expired		(31,600	)		29.78
Unvested as of June 30, 2020		871,787		$	28.40

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

	Six months ended June 30,				Three months ended June 30,
	2020 (unaudited)		2019 (unaudited)		2020 (unaudited)		2019 (unaudited)
Cost of revenue	$	314	$	296	$	156	$	160
Research and development, net		3,345		2,820		1,722		1,458
Sales and marketing		963		750		512		394
General and administrative		1,902		1,229		1,027		667
Total equity-based compensation expense	$	6,524	$	5,095	$	3,417	$	2,679

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

	Six months ended June 30,
	2020 (unaudited)			2019 (unaudited)
Expected dividend yield		0%			0	%
Expected volatility	32%	-	42%		43	%
Risk-free interest rate	1.5%	-	1.9%		2.5	%
Contractual term of up to (months)		24			24