Share Based Award (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of stock compensation and related tax benefits [Table Text Block]

The table below summarizes compensation costs and related tax benefits (in thousands):

	Year ended December 31,
	2023		2022		2021
Stock compensation expense	$	40,563	$	36,025	$	27,341
Tax benefit from stock-based compensation cost	$	5,379	$	4,636	$	6,391
Indirect tax benefit	$	—	$	749	$	285

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

The table below summarizes the total time-based stock options granted, total valuation and the weighted-average assumptions (dollars and shares in thousands, except per option amounts):

	Year ended December 31,
	2022			2021
Number of time-based options granted	7,620			7,910
Grant-date fair value of options granted	$	540		$	528
Weighted-average assumptions for stock option valuation:
Expected term (years)	5.5			5.5
Expected stock price volatility	36.0		%	35.0		%
Risk-free interest rate	3.0		%	0.9		%
Expected dividend yield	—		%	—		%
Weighted-average grant-price per option	$	185.79		$	200.07
Weighted-average grant-date fair value per option	$	70.86		$	66.78

There were no stock options granted during the year ended December 31, 2023.

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

A summary of our stock option activity as of and for the year ended December 31, 2023 is as follows:

	Shares	Weighted-Average Exercise Price Per Share		Weighted-Average Contractual Life (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2022	527,461	$	79.94
Granted	—	$	—
Exercised	(67,633)	$	59.47
Forfeited or expired	—	$	—
Outstanding at December 31, 2023	459,828	$	82.95	1.1	$	11,856
Exercisable at December 31, 2023	459,828	$	82.95	1.1	$	11,856
Vested and expected to vest, December 31, 2023	459,828	$	82.95	1.1	$	11,856

Exercised Options Data [Table Text Block]

The following table presents information regarding stock option activity (in thousands):

	Year ended December 31,
	2023		2022		2021
Intrinsic value of options exercised	$	8,441	$	17,340	$	27,534
Cash received from exercise of stock options	$	4,022	$	8,785	$	9,372
Tax benefit from stock option exercises	$	1,733	$	3,637	$	5,092

Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]

The table below summarizes our restricted stock award activity (dollars in thousands):

	Year ended December 31,
	2023		2022		2021
PRSU
Shares granted	78,213		60,383		53,246
Shares earned (1)	49,314		46,317		32,013
Grant-date fair value per share	$	190.02	$	230.31	$	198.16
Grant-date fair value	$	14,862	$	13,907	$	10,551
Intrinsic value vested	$	8,024	$	10,487	$	6,777
RSU
Shares granted	156,111		116,870		84,388
Grant-date fair value per share	$	173.10	$	221.65	$	199.13
Grant-date fair value	$	27,024	$	25,905	$	16,804
Intrinsic value vested	$	14,179	$	16,438	$	13,681

Nonvested Restricted Stock Shares Activity [Table Text Block]

The table below provides a summary of our PRSU and RSU activity as of and for the year ended December 31, 2023:  

	Number of Units	Grant-Date Fair Value Per Share		Weighted-Average Contractual Life (Years)	Aggregate Intrinsic Value (in thousands)
Non-vested at December 31, 2022	354,004	$	213.95
Change in units due to performance expectations (1)	5,554	$	188.11
Granted	234,324	$	178.75
Vested	(140,091)	$	200.66
Forfeited	(5,190)	$	188.98
Non-vested and expected to vest at December 31, 2023	448,601	$	199.68	0.9	$	44,743