Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition Years

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- Definition

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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- Definition

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

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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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued 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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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 shares authorized for issuance under share-based payment arrangement.

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Net number of share options (or share units) granted during the period.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

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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Share-Based Compensation Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Feb. 10, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted in period		0	0
Weighted average grant date fair value of options granted				$ 16.40
Total unrecognized compensation cost related to unvested share-based compensation arrangements		$ 18.8
Period for recognition (in years)		4 years 6 months
Weighted-average period for recognition		2 years
Performance Incentive Plan 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized		1,750,000
Performance Incentive Plan 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized		2,450,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of stock awarded		$ 109.44	$ 125.34	$ 97.46
Total vesting-date fair value of shares vested during the year		$ 14.4	$ 14.3	$ 11.0
Granted (in shares)		145,178
Grants of common shares and options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Grants of common shares and options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		7 years
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term (in years)		10 years
Restricted stock units \| Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Weighted-average grant-date fair value of stock awarded				$ 97.01
Granted (in shares)	10,441
Restricted stock units \| Minimum \| Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Final award earned percentage of original award	0.00%
Restricted stock units \| Maximum \| Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Final award earned percentage of original award	200.00%