Note 3 - Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Notes Tables

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

	Three Months Ended March 31,
	2021		2020
Cost of revenue	$	816	$	557
Research and development		6,165		4,370
Selling, general and administrative		21,602		13,635
Total stock-based compensation expense	$	28,583	$	18,562
Tax benefit related to stock-based compensation (1)	$	430	$	470

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

	Time-Based RSUs					PSUs and MPSUs					MSUs					Total
	Number of Shares			Weighted- Average Grant Date Fair Value Per Share		Number of Shares			Weighted- Average Grant Date Fair Value Per Share		Number of Shares			Weighted- Average Grant Date Fair Value Per Share		Number of Shares			Weighted- Average Grant Date Fair Value Per Share
Outstanding at January 1, 2021		161		$	151.62		1,390		$	132.60		1,554		$	40.40		3,105		$	87.42
Granted		25		$	374.57		362	(1)	$	351.85		-		$	-		387		$	353.33
Vested		(21	)	$	139.43		(358	)	$	92.39		(81	)	$	23.57		(460	)	$	82.43
Forfeited		(1	)	$	163.87		(10	)	$	86.01		(1	)	$	68.48		(12	)	$	94.88
Outstanding at March 31, 2021		164		$	187.34		1,384		$	200.75		1,472		$	41.31		3,020		$	122.26

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

	Three Months Ended March 31,
	2021			2020
Expected term (in years)		0.5			0.5
Expected volatility		43.3	%		31.4	%
Risk-free interest rate		0.1	%		1.6	%
Dividend yield		0.6	%		1.1	%