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Share-Based Compensation Plans (Textuals) (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Share-based compensation	$ 7.0	$ 7.0	$ 23.0	$ 23.0
Shares Awarded (in shares)			334
Stock-Based Compensation Plans (Textual) [Abstract]
Proceeds from exercise of employee stock options			$ 10.0	$ 7.0
Total intrinsic value of options exercised			11.9
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Unamortized compensation expense	7.0		$ 7.0
Weighted average period			1 year 10 months 24 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award
Unamortized compensation expense	26.0		$ 26.0
Weighted average period			2 years
Shares Awarded (in shares)			284
Performance Based Shares
Share-based Compensation Arrangement by Share-based Payment Award
Unamortized compensation expense	$ 18.0		$ 18.0
Weighted average period			1 year 10 months 24 days