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Number of 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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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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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
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Feb. 08, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining number of shares available for issuance under the plan	6,197,988
Stock-based compensation	$ 17.1	$ 17.0	$ 15.4
Total tax benefit recognized from compensation arrangements	3.2	3.0	2.7
Fair value of shares vested during the period	20.9	$ 18.8	$ 17.6
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount	$ 34.0
Compensation cost is expected to be recognized over a weighted average period, years	3 years 1 month 6 days
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
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period	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	103,307
Number of shares purchased under stock option plan	32,841	22,811
Average price of shares purchased under stock option plan	$ 52.07	$ 64.07
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized				150,000