Share-based Compensation (Summary of Stock Award Information) (Schedule) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assumptions used to estimate fair value of options, SARs and PSARs granted:
Cash received from exercise of options	$ 2.3	$ 5.7	$ 11.7
Income tax benefit related to share-based compensation of our continuing operations (in millions)	$ 21.0	$ 18.6	$ 9.8
Options, SARs and PSARs \| Minimum
Assumptions used to estimate fair value of options, SARs and PSARs granted:
Risk-free interest rate	1.59%	2.68%	1.66%
Expected life	3 years 2 months 12 days	3 years	3 years
Expected volatility	29.90%	30.20%	25.90%
Expected dividend yield	0.00%	0.00%	0.00%
Options, SARs and PSARs \| Maximum
Assumptions used to estimate fair value of options, SARs and PSARs granted:
Risk-free interest rate	2.45%	2.92%	2.16%
Expected life	6 years 2 months 12 days	4 years 2 months 12 days	6 years 4 months 24 days
Expected volatility	33.80%	33.60%	37.90%
Expected dividend yield	0.00%	0.00%	0.00%
Options
Assumptions used to estimate fair value of options, SARs and PSARs granted:
Weighted average grant-date fair value per share of awards granted, options (in dollars per share)	$ 8.60	$ 8.99	$ 9.40
Total intrinsic value of awards exercised	$ 4.2	$ 3.8	$ 13.4
SARs
Assumptions used to estimate fair value of options, SARs and PSARs granted:
Weighted average grant-date fair value per share of awards granted, other than options (in dollars per share)	$ 6.79	$ 7.92	$ 8.60
Total intrinsic value of awards exercised	$ 13.6	$ 22.5	$ 74.8
PSARs
Assumptions used to estimate fair value of options, SARs and PSARs granted:
Weighted average grant-date fair value per share of awards granted, other than options (in dollars per share)	$ 6.92	$ 0	$ 0
RSUs
Assumptions used to estimate fair value of options, SARs and PSARs granted:
Weighted average grant-date fair value per share of awards granted, other than options (in dollars per share)	24.66	28.72	31.24
RSAs
Assumptions used to estimate fair value of options, SARs and PSARs granted:
Weighted average grant-date fair value per share of awards granted, other than options (in dollars per share)	25.29	0	0
PSUs
Assumptions used to estimate fair value of options, SARs and PSARs granted:
Weighted average grant-date fair value per share of awards granted, other than options (in dollars per share)	$ 25.00	$ 23.60	$ 26.59

Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Amount of cash inflow from issuance of shares under share-based payment arrangement. Includes, but is not limited to, option exercised.

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The weighted average fair value at grant date for nonvested equity-based awards issued 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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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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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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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Expected term of 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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