Note 8 - Equity Incentive Plans and Equity (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

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

	Shares			Weighted-Average Grant-Date Fair Value Per Unit
Outstanding at December 31, 2020		170		$	43.60
Granted		47			152.27
Exercised/Vested		(109	)		38.64
Forfeited		(6	)		92.25
Outstanding at December 31, 2021		103		$	96.18

	Shares			Weighted-Average Grant-Date Fair Value Per Unit
Outstanding at December 31, 2020		23		$	55.54
Granted		-			-
Forfeited		(1	)		111.65
Outstanding at December 31, 2021		22		$	111.65

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

	Year Ended December 31,
	2021	2020	2019
Weighted average exercise price of options granted	$ 155.00	$ 135.55	$ 48.64
Expected volatility	50.4%	46.9% - 51.5%	47.6% - 48.5%
Average expected terms in years	6.1	5.8 - 7	6 - 6.6
Risk-free interest rate	1.1%	0.3% - 1.69%	2.27%
Expected dividend yield	0.0%	0.0%	0.0%

Performance Stock Options [Member]

Notes Tables

Share-based Payment Arrangement, Performance Shares, Outstanding Activity [Table Text Block]

Options	Shares			Weighted Average Exercise Price		Average Remaining Contractual Term		Aggregate Intrinsic Value
Outstanding at December 31, 2020		2,119		$	66.19
Granted		101			154.83
Exercised		(153	)		9.82
Forfeited		-			-
Outstanding at December 31, 2021		2,067		$	74.71		7.07	$	87,896
Exercisable at December 31, 2021		975		$	14.03		5.10	$	80,020

Service Period Stock Options [Member]

Notes Tables

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

Options	Shares			Weighted Average Exercise Price		Average Remaining Contractual Term		Aggregate Intrinsic Value
Outstanding at December 31, 2020		1,327		$	45.88
Granted		30			155.60
Exercised		(70	)		10.89
Forfeited		-			-
Outstanding at December 31, 2021		1,287		$	50.37		6.24	$	73,719
Exercisable at December 31, 2021		924		$	22.30		5.27	$	71,047