Income from Continuing Operations Per Unrestricted Share - Reconciliation of Numerator and Denominator in Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net (Loss) Income	$ (301.2)	$ (120.5)	$ 409.9
Dilutive Effect on Income of Equity-based Compensation Equivalent Shares	$ 0.0	$ 0.0	$ 0.0
Weighted-average Unrestricted Shares Outstanding (in shares)	63,825,500	64,264,400	65,636,100
Equity-based Compensation Equivalent Shares (in shares)	0	0	1,093,700
Weighted-average Unrestricted Shares and Equivalent Shares Outstanding Assuming Dilution (in shares)	63,825,500	64,264,400	66,729,800
Basic Income from Continuing Operations Per Unrestricted Share (in dollars per share)			$ 6.24
Diluted Income from Continuing Operations Per Unrestricted Share (in dollars per share)			$ 6.14
Common Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net (Loss) Income	$ (301.2)	$ (120.5)	$ 409.5
Diluted Net (Loss) Income Attributed to Unrestricted Shares	(301.2)	(120.5)	409.5
Participating Awards
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net (Loss) Income	$ 0.0	$ 0.0	$ 0.4