Share-Based Compensation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jul. 31, 2020
Grant Date Fair Value Assumptions [Abstract]
Share-based compensation	$ 15,187,000	$ 14,516,000	$ 13,472,000
Recognized tax benefits	$ (30,000,000)	$ (28,600,000)	$ (23,500,000)
Stock Options [Member]
Stock option activity [Roll Forward]
Beginning balance (in shares)	884,059
Granted (in shares)	44,750
Exercised (in shares)	274,253	482,361	640,475
Forfeited (in shares)	2,939
Ending balance (in shares)	651,617	884,059
Exercisable (In Shares)	376,780
Stock option weighted average exercise price [Abstract]
Beginning balance (in dollars per share)	$ 91.49
Granted (in dollars per share)	332.91
Exercised (in dollars per share)	52.64
Forfeited (in dollars per share)	207.30
Ending balance (in dollars per share)	123.98	$ 91.49
Exercisable at end of period (in dollars per share)	$ 76.06
Weighted Average Remaining Contractual Term [Abstract]
Weighted average remaining contractual term of shares outstanding (in years)	4 years 11 months 4 days
Weighted average remaining contractual term of shares exercisable at end of period (in years)	3 years 3 months 21 days
Aggregate Intrinsic Value [Abstract]
Ending balance	$ 288,028,501
Exercisable at end of period	$ 184,599,877
Cash Proceeds and Tax Benefits [Abstract]
Exercised (in shares)	274,253	482,361	640,475
Cash proceeds	$ 14,435,000	$ 17,657,000	$ 16,839,000
Intrinsic value of options exercised	118,305,000	116,794,000	97,007,000
Tax benefits realized	$ 29,576,000	$ 29,199,000	$ 24,252,000
Grant Date Fair Value Assumptions [Abstract]
Expected volatility (in hundredths)	27.00%	20.70%	21.40%
Expected term (in years)	6 years 10 months 24 days	6 years 9 months 18 days	7 years
Risk-free interest rate (in hundredths)	1.00%	1.22%	2.52%
Expected dividend yield (in hundredths)	1.15%	1.30%	1.30%
Grant date fair value (in dollars per share)	$ 83.05	$ 42.52	$ 37.75
Share-based compensation	$ 2,846,000	$ 2,842,000	$ 3,021,000
Recognized tax benefits	712,000	710,000	755,000
Unamortized compensation expense	$ 3,600,000
Expense recognition over weighted average period (in years)	2 years 9 months 18 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award performance period	3 years
Shares available for grant	933,872
Grant Date Fair Value Assumptions [Abstract]
Share-based compensation	$ 11,543,000	$ 10,965,000	$ 10,026,000
Unamortized compensation expense	$ 14,500,000
Expense recognition over weighted average period (in years)	3 years
Restricted stock awards [Roll Forward]
Beginning balance (in shares)	291,704
Granted (at market price) (in shares)	40,597
Vested (in shares)	69,069	77,294	75,143
Forfeited (in shares)	2,494
Ending balance (in shares)	260,738	291,704
Restricted stock awards weighted average grant date fair value [Abstract]
Beginning balance (in dollars per share)	$ 153.12
Granted (at market price) (in dollars per share)	335.80
Vested (in dollars per share)	115.88
Forfeited (in dollars per share)	295.73
Ending balance (in dollars per share)	$ 190.26	$ 153.12
Vested (in shares)	69,069	77,294	75,143
Fair value of restricted stock awards vested	$ 24,005,000	$ 16,813,000	$ 12,316,000
ESPP Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares purchased under the ESPP (in shares)	8,649	10,929	12,716
Grant Date Fair Value of most recent ESPP Purchase (per share)				$ 121.82
Grant Date Fair Value Assumptions [Abstract]
Share-based compensation	$ 800,000	$ 700,000	$ 400,000
LTIP 2007 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares allocated for issuance (in shares)	9,315,000
Shares available for grant	4,109,524
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares allocated for issuance (in shares)	956,250
Discounted percentage rate offered under the employee stock purchase plan (in hundredths)	85.00%
Minimum [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award performance period, extension period	1 year
Maximum [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award performance period, extension period	2 years