Calculation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Calculation of Basic and Diluted Earnings per Share [Abstract]
Net Income from Continuing Operations	$ 67.6	$ 42.8
Income from discontinued operations, net of income taxes	(0.8)	5.9
Net income	66.8	48.7
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 66.8	$ 48.7
Weighted-average number of common shares outstanding - basic	51.6	53.0
Dilutive effect of common share equivalents	0.7	0.7
Weighted-average number of common shares and share equivalents outstanding - diluted	52.3	53.7
Continuing operations	$ 1.31	$ 0.81
Discontinued operations	(0.01)	0.11
Basic earnings per share:	1.30	0.92
Continuing operations	1.29	0.80
Discontinued operations	(0.01)	0.11
Diluted earnings per share:	$ 1.28	$ 0.91