Note 15 - Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2021

Notes Tables

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

	September 30, 2021			December 31, 2020
Risk–free interest rate		0.21	%		0.87	%
Expected volatility		35.1	%		20.1	%
Expected life, in years		2.2			2.2
Expected dividend yield		3.01	%		2.91	%

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

	Number of Shares			Weighted Average Exercise Price		Aggregate Intrinsic Value
Options outstanding at January 1, 2020		809,529		$	71.24	$	–
Options granted		104,057			73.98		–
Options exercised		(43,630	)		63.37		–
Options cancelled		(3,000	)		72.94		–
Options outstanding at December 31, 2020		866,956			72.11		–
Options granted		56,795			70.73		–
Options exercised		(148,900	)		68.41		–
Options cancelled		(6,000	)		72.94		–
Options outstanding at September 30, 2021		768,851		$	72.72	$	656,425
Options exercisable at September 30, 2021		177,686		$	69.38	$	587,578

Share-based Payment Arrangement, Option, Exercise Price Range [Table Text Block]

Options Outstanding September 30, 2021	Exercise Prices			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life in Years
103,775	60.73	-	67.28		63.65		2.3
665,076	71.64	-	84.30		74.14		0.9
768,851					72.72		1.0