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, 2020	Mar. 31, 2019
Basic earnings per share:
Income from continuing operations	$ 29.0	$ 19.7
Weighted average number of shares outstanding (in shares)	31.9	31.8
Basic earnings per share from continuing operations (in dollars per share)	$ 0.91	$ 0.62
Diluted earnings per share:
Income from continuing operations	$ 29.0	$ 19.7
Weighted average number of shares outstanding (in shares)	31.9	31.8
Effect of dilutive securities:
Restricted stock (in shares)	0.2	0.2
Total shares and dilutive securities (in shares)	32.1	32.0
Diluted earnings per share from continuing operations (in dollars per share)	$ 0.90	$ 0.62