Note 9 - Share-based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

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

	2021			2020			2019
Expected dividend yield at date of grant		2.15	%		1.84	%		2.60	%
Expected stock price volatility		34.85	%		33.62	%		34.01	%
Risk-free interest rate		0.91	%		1.35	%		2.38	%
Expected life of options (in years)		7.01			7.39			7.46

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

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Terms (Years)		Aggregate Intrinsic Value (In thousands)
Common Stock
Outstanding at December 31, 2020		600,571		$	25.31
Granted		101,091		$	44.96
Exercised		(116,753	)	$	13.14			$	3,535
Expired		(22,837	)		9.74
Forfeited		(84,432	)	$	38.38
Outstanding at December 31, 2021		477,640		$	30.88		5.97	$	6,337
Exercisable at December 31, 2021		249,488		$	23.99		4.82	$	4,805

Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value, Intrinsic Value of Exercised and Vested in Period, and Fair Value of Vested in Period [Table Text Block]

	2021		2020		2019
Weighted average grant date fair value of stock options granted	$	12.55	$	18.67	$	11.99
Intrinsic value of stock options exercised (in thousands)	$	3,535	$	25,912	$	8,280
Intrinsic value of stock options vested (in thousands)	$	4,805	$	1,965	$	1,891

Schedule of Nonvested Share Activity [Table Text Block]

	Common Stock Outstanding			Common Stock Weighted Average Grant Date Fair Value Per Share
Outstanding at December 31, 2020		6,005		$	38.30
Granted		12,698		$	42.92
Vested		--		$	--
Forfeited		(6,005	)	$	38.30
Outstanding at December 31, 2021		12,698		$	42.92