Share-based Compensation and Non-Qualified Deferred Compensation Plan (Summary Of Share Incentive Plans) (Details) - $ / shares	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested share awards outstanding at December 31, 2018, Share Awards Outstanding	264,654
Granted, Share Awards Outstanding	157,948
Exercised/Vested, Share Awards Outstanding	(174,846)
Forfeited, Share Awards Outstanding	(1,752)
Nonvested share awards outstanding at September 30, 2019, Share Awards Outstanding	246,004
Nonvested share awards outstanding at December 31, 2018, Weighted Average Exercise/Grant Price	$ 90.44
Granted, Weighted Average Exercise/Grant Price	117.70	$ 98.58
Exercised/Vested, Weighted Average Exercise/Grant Price	96.34
Forfeited, Weighted Average Exercise/Grant Price	102.24
Nonvested share awards outstanding at September 30, 2019, Weighted Average Exercise/Grant Price	$ 103.67

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=116856206&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
-Subparagraph (c)(2)(iii)(3)
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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
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
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- Definition

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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- 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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-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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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.

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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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