Income (Loss) from Continuing Operations Per Unrestricted Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Schedule of Basic and Diluted Earnings Per Share [Line Items]
Income (Loss) from Continuing Operations	$ 53.6	$ (0.4)
Dilutive Effect on Income of Equity-based Compensation Equivalent Shares	0.0	0.0
Diluted Income (Loss) from Continuing Operations Attributed to Unrestricted Shares	$ 53.1	$ (0.3)
Weighted-Average Unrestricted Shares Outstanding (shares)	51,502,900	51,273,100
Equity-based Compensation Equivalent Shares (shares)	365,300	0
Weighted-Average Unrestricted Shares and Equivalent Shares Outstanding Assuming Dilution (shares)	51,868,200	51,273,100
Basic Income (Loss) from Continuing Operations Per Unrestricted Share	$ 1.03	$ (0.01)
Diluted Income (Loss) from Continuing Operations Per Unrestricted Share	$ 1.02	$ (0.01)
Unrestricted Shares [Member]
Schedule of Basic and Diluted Earnings Per Share [Line Items]
Income (Loss) from Continuing Operations	$ 53.1	$ (0.3)
Participating Awards [Member]
Schedule of Basic and Diluted Earnings Per Share [Line Items]
Income (Loss) from Continuing Operations	$ 0.5	$ (0.1)