Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net Income (Loss) Attributable to Parent	$ 88.8	$ 64.2	$ 231.4	$ 248.6
Less Undistributed Earnings (Loss) Allocated to Nonvested Stock	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Denominator:
Weighted Average Number of Shares Outstanding, Basic	75,223,462	75,628,410	75,288,567	75,864,544
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	1,062,674	964,284	843,353	1,037,882
Weighted average number of shares outstanding, assuming dilution of stock options and awards	76,286,136	76,592,694	76,131,920	76,902,426
Basic earnings per share	$ 1.18	$ 0.85	$ 3.07	$ 3.28
Diluted earnings per share	$ 1.16	$ 0.84	$ 3.04	$ 3.23