Common stock dividend rate percentage.

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Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period, Contractual Terms

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

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

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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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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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Number of additional shares authorized for issuance under share-based payment arrangement.

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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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Per share weighted-average price paid for shares purchased on open market for issuance under share-based payment arrangement.

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Number of shares purchased for issuance under share-based payment arrangement.

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Weighted average remaining contractual term for fully vested and expected to vest exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Stock-Based Compensation and Directors Stock Purchase Plan (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Feb. 08, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining number of shares available for issuance under the plan		1,839,368
Stock-based compensation		$ 15.4	$ 14.9	$ 13.9
Total tax benefit recognized from compensation arrangements		2.7	3.0	3.0
Fair value of shares vested during the period		17.6	$ 18.0	$ 19.9
Unrecognized compensation cost related to unvested SAR's and stock awards		$ 29.5
Compensation cost is expected to be recognized over a weighted average period, years		3 years
Common stock dividend rate percentage		5.00%
Nonvested Stock Award [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vesting period (in years)		4 years
Nonvested Stock Award [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vesting period (in years)		7 years
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards vesting period (in years)		4 years
Contractual terms of awards granted (in years)		10 years
Directors Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining number of shares available for issuance under the plan		755
Number of shares purchased under stock option plan		13,388	22,904
Average price of shares purchased under stock option plan		$ 69.15	$ 57.67
Increase to Shares Authorized, Director's Stock \| Directors Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	150,000