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

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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, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated share-based compensation expense		$ 4.4	$ 4.0	$ 10.6	$ 9.1
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				78,218
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, weighted average grant date fair value				$ 89.00
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized		12.6		$ 12.6
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition				1 year 9 months 18 days
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				50,735
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, weighted average grant date fair value				$ 89.12
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized		9.3		$ 9.3
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				35,318
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, weighted average grant date fair value				$ 95.72
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized		$ 4.4		$ 4.4
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			37,077
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		1,005,607		1,005,607