Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Basic earnings per share:
Income from continuing operations	$ 1.6	$ 17.6
Weighted average number of shares outstanding (in shares)	31.9	30.0
Basic earnings per share from continuing operations (in dollars per share)	$ 0.05	$ 0.59
Diluted earnings per share:
Income from continuing operations	$ 1.6	$ 17.6
Weighted average number of shares outstanding (in shares)	31.9	30.0
Effect of dilutive securities:
Restricted stock (in shares)	0.5	0.4
Total shares and dilutive securities (in shares)	32.4	30.4
Diluted earnings per share from continuing operations (in dollars per share)	$ 0.05	$ 0.58