Weighted Average Shares Outstanding (Schedule of Weighted Average Shares Outstanding) (Details) - shares shares in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Basic shares outstanding (in shares)	104.3	103.6
Effect of potential common stock:
Common stock awards (in shares)	1.0	1.1
Diluted shares outstanding (in shares)	105.3	104.7

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- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

+ References

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-Name Accounting Standards Codification
-Topic 260
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- References

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- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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