Stock-Based Compensation (Summary Of Restricted Stock Activity) (Details) - Restricted Stock [Member]	3 Months Ended
Mar. 31, 2019 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value \| $	$ 44,836
Outstanding at January 1, 2019 (non-vested) \| shares	1,196,914
Granted \| shares	30,739
Vesting (transfer/conversion to common stock) \| shares	(910)
Forfeited \| shares	(3,625)
Outstanding at March 31, 2019 (non-vested) \| shares	1,223,118
Outstanding at January 1, 2019 (non-vested), Weighted Average Grant Date Fair Value \| $ / shares	$ 46.81
Granted, Weighted Average Grant Date Fair Value \| $ / shares	55.16
Vesting and transfer of ownership to recipients, Weighted Average Grant Date Fair Value \| $ / shares	49.36
Forfeited, Weighted Average Grant Date Fair Value, per share \| $ / shares	41.21
Outstanding at March 31, 2019 (non-vested), Weighted Average Grant Date Fair Value \| $ / shares	$ 47.03
Aggregate Intrinsic Value \| $	$ 60,263,000
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement Vesting Period	3 years

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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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.

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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).

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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).

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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.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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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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- 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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Intrinsic value of equity-based compensation awards outstanding. Excludes stock and unit options.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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