Stock-Based Compensation (Summary Of Performance Share Unit Activity) (Details) - Performance Shares [Member] $ / shares in Units, $ in Millions	6 Months Ended
Jun. 30, 2020 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares, Issued	7,889
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value \| $	$ 0.5
Outstanding at January 1, 2020 (non-vested)	375,588
Vesting and transfer of ownership to recipients	(12,129)
Forfeited	(18,766)
Outstanding at June 30, 2020 (non-vested)	325,243
Total unrecognized compensation cost related to non-vested grants \| $	$ 8.3
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value \| $ / shares	$ 58.07
Total unrecognized compensation cost, weighted-average period of recognition, years	1 year 7 months 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Other Increases (Decreases) in Period	(19,450)
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage Of Share Units Awarded Ultimately Issued	0.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage Of Share Units Awarded Ultimately Issued	200.00%

Percentage Of Share Units Awarded Ultimately Issued

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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

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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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The addition or reduction in the number of reserved shares that could potentially be issued under the option plan attributable to reasons other than grants, exercises, forfeitures, and expirations during the reporting period.

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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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Number of shares of stock issued as of the balance sheet date, including shares that had been issued and were previously outstanding but which are now held in the treasury.

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