Share-Based Compensation Plans (Textuals) (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award
Share-based compensation	$ 8.0	$ 9.0
Shares Awarded (in shares)	334
Stock-Based Compensation Plans (Textual) [Abstract]
Proceeds from exercise of employee stock options	$ 5.0	$ 4.0
Total intrinsic value of options exercised	5.6
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Unamortized compensation expense	$ 9.0
Weighted average period	2 years 3 months 18 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award
Unamortized compensation expense	$ 29.0
Weighted average period	2 years 2 months 12 days
Shares Awarded (in shares)	219
Performance Based Shares
Share-based Compensation Arrangement by Share-based Payment Award
Unamortized compensation expense	$ 15.0
Weighted average period	2 years 4 months 24 days

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Amount of cash inflow from exercise of option under share-based payment arrangement.

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Amount of noncash expense for share-based payment arrangement.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Gross number of share options (or share units) granted during the period.

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Stock-based compensation plans.

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