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

3 Months Ended

Mar. 31, 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		(161,001	)		17.55
Forfeited or expired		—			—
Outstanding as of March 31, 2020 (2)		481,252		$	21.01		3.4	$	2,524
Exercisable as of March 31, 2020 (3)		455,252		$	20.59		3.2	$	2,524

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		386,237			27.46
Vested		(222,006	)		32.21
Forfeited or expired		(14,741	)		28.74
Unvested as of March 31, 2020		882,054		$	28.45

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

	Three months ended March 3 1 ,
	20 20 (unaudited)		201 9 (unaudited)
Cost of revenue	$	158	$	136
Research and development, net		1,623		1,362
Sales and marketing		451		356
General and administrative		875		562
Total equity-based compensation expense	$	3,107	$	2,416

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

	Three months ended March 3 1 ,
	20 20 (unaudited)			201 9 (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