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

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

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Accounting for Stock-based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		6 Months Ended
	Apr. 04, 2018	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated share-based compensation expense		$ 4.4	$ 4.4	$ 9.0	$ 10.6
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period				117,196
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, weighted average grant date fair value				$ 91.79
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized		16.4		$ 16.4
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition				2 years
Cash Settled RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period				62,840
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, weighted average grant date fair value				$ 92.40
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized		8.4		$ 8.4
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition				1 year 9 months 18 days
Performance Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period				35,705
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, weighted average grant date fair value				$ 93.97
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized		$ 5.2		$ 5.2
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition				1 year 4 months 24 days
Omnibus Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares grants	1,600,000			22,333
Share-based compensation arrangement by share-based payment award, number of additional awards				0
Share-based compensation arrangement by share-based payment award, number of shares available for grant		812,251		812,251