Note 5 - Share-based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Notes Tables

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

	2020			2019
Expected dividend yield at date of grant		1.84	%		2.60	%
Expected stock price volatility		33.62	%		34.01	%
Risk-free interest rate		1.35	%		2.38	%
Expected life of options (in years)		7.4			7.5

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)
Outstanding at December 31, 2019		1,245,922		$	18.08		4.45	$	59,631
Granted		70,471		$	62.23
Exercised		(408,765	)	$	12.68			$	17,810
Forfeited		(15,490	)	$	48.42
Outstanding at June 30, 2020		892,138		$	23.51		5.77	$	31,281
Exercisable at June 30, 2020		492,484		$	17.55		4.58	$	20.022

Schedule of Nonvested Share Activity [Table Text Block]

	Common Shares Outstanding			Weighted Average Grant Date Fair Value Per Share
Outstanding at December 31, 2019		84,176		$	17.23
Granted		-			-
Vested		(34,622	)		13.17
Forfeited		(6,793	)	$	36.80
Outstanding at June 30, 2020		42,761		$	17.40