Note 3 - Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2021

Notes Tables

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
Cost of revenue	$	922	$	707	$	2,622	$	1,906
Research and development		6,646		5,334		19,564		14,666
Selling, general and administrative		24,004		16,934		70,096		46,009
Total stock-based compensation expense	$	31,572	$	22,975	$	92,282	$	62,581
Tax benefit related to stock-based compensation (1)	$	488	$	512	$	1,299	$	1,450

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		43		$	375.33		365	(1)	$	352.37		-		$	-		408		$	354.79
Vested		(60	)	$	142.13		(504	)	$	91.73		(243	)	$	23.57		(807	)	$	74.95
Forfeited		(9	)	$	199.05		(12	)	$	100.25		(9	)	$	68.48		(30	)	$	118.31
Outstanding at September 30, 2021		135		$	223.71		1,239		$	214.52		1,302		$	43.33		2,676		$	131.68

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

	Three Months Ended September 30,						Nine Months Ended September 30,
	2021			2020			2021			2020
Expected term (in years)		0.5			0.5			0.5			0.5
Expected volatility		43.0	%		66.4	%		43.2	%		48.9	%
Risk-free interest rate		0.1	%		0.1	%		0.1	%		0.8	%
Dividend yield		0.5	%		0.7	%		0.6	%		0.9	%