Share-Based Compensation and Benefit Plans (Stock Appreciation Rights) (Narrative) (Details) - Stock appreciation rights (SARs) [Member] $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020 USD ($) shares	Sep. 30, 2020 USD ($) shares
Share-Based Compensation and Benefit Plans
Stock appreciation rights expiration period		10 years
Stock appreciation rights vesting rate per year		25.00%
Vesting period		4 years
Stock appreciation rights outstanding \| shares	7,486	7,486
Stock appreciation rights granted during the period, units \| shares		348
Liability for compensation to be paid for redeemed stock appreciation rights \| $	$ 0.2	$ 0.2
Compensation expense for share-based compensation \| $	$ 0.1	$ 0.2

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Aggregate carrying value as of the balance sheet date of the liabilities for stock option plans and other equity-based compensation arrangements.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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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 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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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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Percentage of vesting of award under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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