Note 13 - Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2019

Notes Tables

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

	September 30, 2019		December 31, 2018
Risk–free interest rate		2.30%		2.46%
Expected volatility		17.4%		16.1%
Expected life, in years		2.3		3.0
Expected dividend yield		2.73%		3.29%

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

	Number of Shares			Weighted Average Exercise Price		Aggregate Intrinsic Value
Options outstanding at January 1, 2018		1,239,407		$	71.19	$	–
Options granted		110,265			61.39		–
Options exercised		(68,291	)		54.31		–
Options cancelled		(118,000	)		72.11		–
Options outstanding at December 31, 2018		1,163,381			71.16		–
Options granted		53,628			77.89		–
Options exercised		(332,852	)		71.56		–
Options cancelled		(85,000	)		72.94		--
Options outstanding at September 30, 2019		799,157		$	71.25	$	8,468,000
Options exercisable at September 30, 2019		209,029		$	68.05	$	2,885,000

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

Options Outstanding September 30, 2019	Exercise Prices			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life in Years
144,968	60.73	-	62.78		61.81		2.3
654,189	72.94	-	77.92		73.35		2.6
799,157					71.25		2.5