Stock-based Compensation (Summary of Activity Information about Employee Restricted Stock Units) (Details) - $ / shares	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Time-Based Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, beginning of period, Shares	380,100	350,480
Granted, Shares	143,208	168,092
Vested, Shares	(114,978)	(109,667)
Forfeited, Shares	(5,609)	(7,388)
Outstanding, end of period, Shares	402,721	401,517
Outstanding, beginning of period, Weighted Average Grant Date Fair Value	$ 117.60	$ 116.37
Granted, Weighted Average Grant Date Fair Value	138.20	115.04
Vested, Weighted Average Grant Date Fair Value	119.35	110.68
Forfeited, Weighted Average Grant Date Fair Value	119.92	116.82
Outstanding, end of period, Weighted Average Grant Date Fair Value	$ 124.40	$ 117.37
Performance-Based and Market-Based Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, beginning of period, Shares	113,848	97,043
Granted, Shares	47,954	62,143
Vested, Shares	(39,338)	(43,506)
Forfeited, Shares	(2,936)
Outstanding, end of period, Shares	119,528	115,680
Outstanding, beginning of period, Weighted Average Grant Date Fair Value	$ 115.92	$ 119.59
Granted, Weighted Average Grant Date Fair Value	140.36	114.66
Vested, Weighted Average Grant Date Fair Value	124.42	122.27
Forfeited, Weighted Average Grant Date Fair Value	121.73
Outstanding, end of period, Weighted Average Grant Date Fair Value	$ 122.78	$ 115.93

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Paragraph 2
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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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-Publisher FASB
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-Topic 718
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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

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-Publisher FASB
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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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