The maximum period over which the fair value of restricted stock and restricted stock units are amortized.

No definition available.

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- Definition

The historical period upon which annual expected stock price volatility is based.

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Represents the daily treasury yield curve period, in years, upon which the average risk-free interest rate is based.

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Share Based Compensation Arrangement by Share Based Payment Award, Number of Shares Available for Grant Decrease

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

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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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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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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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- 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 difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Shareholders' Equity and Long-Term Incentive Compensation - Long-Term Incentive Compensation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock-based Compensation
Historical period upon which annual expected stock price volatility is based (years)	3 years
Maximum
Stock-based Compensation
Maximum period over which the fair value of restricted stock shares and restricted stock units are amortized	3 years
Daily treasury yield curve period upon which average risk-free interest rate is based (years)	3 years
Maximum \| 2019 Stock Compensation Plan
Stock-based Compensation
Shares available for grant (in shares)	4,074,000.000
Minimum
Stock-based Compensation
Daily treasury yield curve period upon which average risk-free interest rate is based (years)	1 year
Restricted stock shares and restricted stock units \| 2019 Stock Compensation Plan
Stock-based Compensation
Reduction of shares available for grant (in shares)	2
Restricted stock shares and restricted stock units \| Directors' Plan
Stock-based Compensation
Vesting period (years)	1 year	1 year	1 year
Restricted stock shares and restricted stock units \| Maximum \| Directors' Plan
Stock-based Compensation
Shares available for grant (in shares)	27,000.000
PSU's, RSU's, and RS's
Stock-based Compensation
Unrecognized compensation cost related to PSUs, RSUs, and RSs	$ 10.9
PSU's, RSU's, and RS's \| Maximum
Stock-based Compensation
Vesting period (years)	3 years
PSU's, RSU's, and RS's \| Minimum
Stock-based Compensation
Vesting period (years)	1 year
PSU's, RSU's, and RS's \| Weighted Average
Stock-based Compensation
Weighted-average period over which unrecognized compensation costs will be recognized	1 year 9 months 18 days
PSU's
Stock-based Compensation
Vesting period (years)	3 years
PSU's, RSU's, RS's, and Stock Options
Stock-based Compensation
Long-term incentive compensation expense	$ 12.9	$ 12.0	$ 10.0
Related tax benefit	2.2	2.0	2.4
Long Term Cash Awards
Stock-based Compensation
Vesting period (years)				3 years
Long-term incentive compensation expense	$ (0.1)	$ 1.1	$ 2.6