Share-Based Compensation and Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2020

Share-Based Compensation and Benefit Plans

Summary of shares authorized and available for future issuance under compensation and benefit plans

	December 31, 2020
	Total Shares Authorized for	Shares Available for Future
Plans	Issuance under the Plans	Issuance under the Plans
Incentive Plans	34,650	5,592
Employee Stock Purchase Plan	4,250	506
Profit Sharing and Savings Plan	4,200	349

Restricted stock [Member]

Share-Based Compensation and Benefit Plans

Summary of activity of share-based compensation and benefit plans

	For the Year Ended
	December 31,
	2020		2019		2018
Compensation expense for restricted shares awarded	$	1,488	$	1,387	$	1,370
Income tax benefit from compensation expense related to restricted shares	$	373	$	341	$	340
Total fair value of restricted shares at vest date	$	1,591	$	1,633	$	1,230
Shares awarded under the plans		4		4		5
Weighted-average grant-date fair value of shares awarded under the plans	$	412.67	$	355.91	$	263.89

Employee stock purchase plan [Member]

Share-Based Compensation and Benefit Plans

Summary of ESPP plan activity

	For the Year Ended
	December 31,
	2020		2019		2018
Compensation expense for shares issued under the ESPP	$	2,824	$	2,490	$	2,285
Income tax benefit from compensation expense related to shares issued under the ESPP	$	708	$	612	$	566
Shares issued under the ESPP		45		43		53
Weighted-average price of shares issued under the ESPP	$	353.04	$	329.69	$	245.26

Employee [Member] | Restricted stock [Member]

Share-Based Compensation and Benefit Plans

Summary of restricted stock

		Weighted-Average Grant-Date
	Shares	Fair Value
Non-vested at December 31, 2019	4	$	301.40
Granted during the period	2		419.88
Vested during the period (1)	(2)		289.03
Forfeited during the period	—		—
Non-vested at December 31, 2020	4	$	358.58

Director [Member] | Restricted stock [Member]

Share-Based Compensation and Benefit Plans

Summary of restricted stock

		Weighted-Average Grant-Date
	Shares	Fair Value
Non-vested at December 31, 2019	4	$	312.96
Granted during the period	2		407.12
Vested during the period	(2)		293.72
Forfeited during the period	—		—
Non-vested at December 31, 2020	4	$	371.46

Stock option [Member]

Share-Based Compensation and Benefit Plans

Black-Scholes option pricing model

	December 31,
	2020		2019		2018
Risk free interest rate	0.86	%	2.26	%	2.63	%
Expected life	5.9	Years	5.7	Years	5.9	Years
Expected volatility	26.4	%	25.1	%	24.0	%
Expected dividend yield	—	%	—	%	—	%

Summary of activity of share-based compensation and benefit plans

	For the Year Ended
	December 31,
	2020		2019		2018
Compensation expense for stock options awarded (in thousands)	$	18,435	$	18,044	$	16,521
Income tax benefit from compensation expense related to stock options (in thousands)		4,620		4,436		4,093
Total intrinsic value of stock options exercised (in thousands)		79,451		117,489		156,327
Cash received from exercise of stock options (in thousands)		46,282		46,106		61,403
Weighted-average grant-date fair value of options awarded	$	106.76	$	105.37	$	76.57
Weighted-average remaining contractual life of exercisable options (in years)		4.5		4.6		4.4

Stock option [Member] | Employee stock option [Member]

Share-Based Compensation and Benefit Plans

Summary of stock options

				Average		Aggregate
	Shares	Weighted- Average		Remaining		Intrinsic Value
	(in thousands)	Exercise Price		Contractual Terms		(in thousands)
Outstanding at December 31, 2019	1,635	$	218.10
Granted	175		394.79
Exercised	(288)		160.67
Forfeited or expired	(22)		302.55
Outstanding at December 31, 2020	1,500	$	248.52	5.7	Years	$	306,095
Vested or expected to vest at December 31, 2020	1,470	$	246.44	5.7	Years	$	302,927
Exercisable at December 31, 2020	988	$	202.19	4.5	Years	$	247,419