Note 18 - Share-based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

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

	2020			2019			2018
Expected volatility		27 - 32	%		26 - 27	%		25	%
Weighted-average expected volatility		27	%		26	%		25	%
Expected dividend yield		1.3	%		1.2 - 1.4	%		1.2	%
Weighted-average expected dividend yield		1.3	%		1.2	%		1.2	%
Expected term, in years		5			5			5
Risk-free interest rate		0.3 - 1.3	%		1.6 - 2.5	%		2.6 - 2.9	%

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

	Shares			Weighted-Average Exercise Price
Outstanding at beginning of year		1,071,777		$	60.01
Granted		76,251			81.20
Exercised		(110,595	)		44.29
Forfeited		(42,083	)		70.83
Expired		(4,687	)	$	68.01
Outstanding at end of year		990,663		$	62.90
Exercisable at end of year		767,655		$	61.04

Nonvested Restricted Stock Shares Activity [Table Text Block]

	Shares			Weighted-Average Grant Date Fair Value
Nonvested at beginning of year		93,599		$	54.27
Granted		17,348			81.07
Vested		(10,038	)		73.20
Forfeited		(6,866	)		73.19
Nonvested at end of year		94,043		$	55.81

Schedule of Nonvested Performance-based Units Activity [Table Text Block]

	Shares			Weighted-Average Grant Date Fair Value
Nonvested at beginning of year		120,714		$	67.45
Granted		55,142			76.66
Vested		(29,595	)		72.82
Forfeited		(22,042	)		70.72
Nonvested at end of year		124,219		$	69.68

Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]

	Shares			Weighted-Average Grant Date Fair Value
Nonvested at beginning of year		103,287		$	64.72
Granted		42,248			69.93
Vested		(37,389	)		70.46
Forfeited		(10,661	)		63.11
Nonvested at end of year		97,485		$	64.95