Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Basic earnings per share:
Income from continuing operations	$ 17.2	$ 33.5	$ 78.7	$ 87.2
Weighted average number of shares outstanding (in shares)	32.0	31.9	32.0	31.9
Basic earnings per share from continuing operations (in dollars per share)	$ 0.54	$ 1.05	$ 2.46	$ 2.74
Diluted earnings per share:
Income from continuing operations	$ 17.2	$ 33.5	$ 78.7	$ 87.2
Weighted average number of shares outstanding (in shares)	32.0	31.9	32.0	31.9
Effect of dilutive securities:
Restricted stock (in shares)	0.1	0.2	0.1	0.1
Total shares and dilutive securities (in shares)	32.1	32.1	32.1	32.0
Diluted earnings per share from continuing operations (in dollars per share)	$ 0.54	$ 1.04	$ 2.45	$ 2.72