Stock-based Compensation Expense (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement, Noncash Expense [Abstract]

Fixed-Price Stock Options

The following table summarizes information about the Company’s fixed-price stock options as of and for the year ended December 31, 2023:

	Shares	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2022	384,936	$	114.24	6.3	$	39,501
Granted	51,316	249.52
Exercised	(3,124)	59.41
Forfeited	(5,984)	207.12
Outstanding at December 31, 2023	427,144	$	129.59	5.8	$	14,891
Exercisable at December 31, 2023	314,745	$	102.14	4.9	$	14,891

Weighted-Average Assumptions used to Estimate Fair Value of Each Option Granted

The fair value of each option granted during the years ended December 31, 2023, 2022 and 2021 was estimated on the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions:

	Year Ended December 31,
	2023			2022			2021
Dividend yield	1.26		%	1.32		%	1.43		%
Volatility	40.06		%	36.21		%	36.19		%
Average expected life (years)	6			6			6
Risk-free interest rate	3.95		%	1.97		%	1.44		%
Fair value of options granted	$	98.66		$	63.00		$	49.42

The calculation used the following weighted-average assumptions:

	Year Ended December 31,
	2023		2022		2021
Volatility	50.41	%	51.51	%	47.13	%
Risk-free interest rate	4.51	%	1.72	%	0.27	%

Activity in Performance Unit Awards

The following table summarizes activity in performance unit awards as of and for the year ended December 31, 2023:

	Shares	Weighted-Average Grant Date Fair Value Per Share
Nonvested, beginning of period	224,548	$	140.44
Granted	79,396	288.28
Vested	(73,060)	102.29
Forfeited	(7,028)	229.70
Nonvested, end of period	223,856	207.61

Activity in Non-Performance Based Restricted Stock Awards

The following table summarizes activity in non-performance based restricted stock and restricted stock unit awards as of and for the year ended December 31, 2023:

	Shares	Weighted-Average Grant Date Fair Value Per Share
Nonvested, beginning of period	300,953	$	120.09
Granted	87,240	221.86
Vested	(183,258)	86.15
Forfeited	(6,788)	196.00
Nonvested, end of period	198,147	190.40