Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net income from continuing operations	$ 40.1	$ 48.2	$ 82.1	$ 132.4
Net income	$ 40.1	$ 47.9	$ 82.1	$ 133.5
Denominator:
Denominator for basic earnings per share — weighted average shares	35.5	35.0	35.4	34.9
Effect of dilutive securities:
Equity compensation plans	0.5	0.4	0.6	0.5
Weighted-average shares outstanding - diluted	36.0	35.4	36.0	35.4
Basic earnings per share from continuing operations (in dollars per share)	$ 1.13	$ 1.38	$ 2.32	$ 3.79
Basic earnings per share from discontinued operations (in dollars per share)	0	(0.01)	0	0.03
Basic earnings per share from consolidated operations (in dollars per share)	1.13	1.37	2.32	3.82
Diluted earnings per share from continuing operations (in dollars per share)	1.11	1.36	2.28	3.74
Diluted earnings per share from discontinued operations (in dollars per share)	0	(0.01)	0	0.03
Diluted earnings per share from discontinued operations (in dollars per share)	$ 1.11	$ 1.35	$ 2.28	$ 3.77