Note 5 - Share-based Compensation5 (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Years ended December 31,
	2022		2021		2020
Restricted share units
Pretax compensation expense	$	54,276	$	44,505	$	47,044
Tax benefit		13,216		10,637		11,300
Restricted share units, net of tax	$	41,060	$	33,868	$	35,744
Performance share units
Pretax compensation expense	$	23,259	$	17,000	$	13,654
Tax benefit		5,664		4,063		3,280
Performance share awards, net of tax	$	17,595	$	12,937	$	10,374

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

Restricted Share Units	Number of Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2019		1,313,418		$	91.22
Granted		511,859			110.49
Vested		(457,437	)		93.78
Forfeited		(22,694	)		102.03
Unvested at December 31, 2020		1,345,146		$	97.22
Granted		360,734			150.33
Vested		(387,948	)		100.36
Forfeited		(27,700	)		118.20
Unvested at December 31, 2021		1,290,232		$	110.83
Granted		317,751			189.66
Vested		(427,942	)		118.00
Forfeited		(38,704	)		138.94
Unvested at December 31, 2022		1,141,337		$	129.75

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

Performance Share Units	Number of Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2019		375,528		$	95.67
Granted		202,023			112.87
Vested		(145,038	)		89.75
Forfeited		(98,588	)		110.19
Unvested at December 31, 2020		333,925		$	109.57
Granted		135,500			143.32
Vested		(95,415	)		103.21
Forfeited		-			-
Unvested at December 31, 2021		374,010		$	123.42
Granted		135,842			189.05
Vested		(108,823	)		117.57
Forfeited		-			-
Unvested at December 31, 2022		401,029		$	146.96