Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Income from continuing operations	$ 219.3	$ 266.9	$ 231.8
Income from discontinued operations, net of income taxes	0.0	1.2	178.1
Net income	$ 219.3	$ 268.1	$ 409.9
Weighted Average Number of Shares Outstanding Reconciliation
Weighted-average number of common shares outstanding - basic	48.3	50.6	52.7
Dilutive effect of common share equivalents	0.4	0.7	0.8
Weighted Average Number of Shares Outstanding, Diluted, Total	48.7	51.3	53.5
Continuing operations (in dollars per share)	$ 4.54	$ 5.27	$ 4.40
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	0.03	3.38
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share	0
Earnings per share (in dollars per share)	4.54	5.30	7.78
Continuing operations (in dollars per share)	4.50	5.21	4.33
Discontinued operations (in dollars per share)	0	0.02	3.33
Earnings per share (in dollars per share)	$ 4.50	$ 5.23	$ 7.66