Capital Stock and Equity Compensation (Monte Carlo Calculation Assumptions) (Details) - Performance-Based Restricted Stock Units	Jun. 03, 2019	Feb. 07, 2019	Sep. 17, 2018	Feb. 08, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (percent)	39.70%	36.70%	36.60%	34.80%
Expected term (in years)	2 years 7 months 6 days	2 years 10 months 24 days	3 years	3 years
Risk-free interest rate (percent)	1.78%	2.43%	2.85%	2.28%

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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- Definition

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

+ References

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- Definition

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.

+ References

No definition available.

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- Definition

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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