Earnings (Loss) per Common Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings (Loss) per Common Share
Income (loss) from continuing operations, basic	$ 0.5	$ (21.2)	$ 10.2	$ (66.4)
Income (loss) from continuing operations, diluted	0.5	(21.2)	10.2	(66.4)
Income from discontinued operations, basic		539.1		606.3
Income from discontinued operations, diluted		539.1		606.3
Net income, basic	0.5	517.9	10.2	539.9
Net income, diluted	$ 0.5	$ 517.9	$ 10.2	$ 539.9
Basic weighted-average shares	84,274,050	82,973,519	83,908,691	82,615,949
Effect of dilutive securities
Restricted stock awards	2,461,196		2,763,184
Diluted weighted-average shares	86,735,246	82,973,519	86,671,875	82,615,949
Basic and diluted earnings (loss) per common share - continuing operations
Basic (in dollars per share)	$ 0.01	$ (0.26)	$ 0.12	$ (0.80)
Diluted (in dollars per share)	0.01	(0.26)	0.12	(0.80)
Basic and diluted earnings per common share - discontinued operations
Basic (in dollars per share)		6.50		7.34
Diluted (in dollars per share)		6.50		7.34
Basic and diluted earnings per common share
Basic (in dollars per share)	0.01	6.24	0.12	6.54
Diluted (in dollars per share)	$ 0.01	$ 6.24	$ 0.12	$ 6.54