Stock-Based Compensation (Schedule of Weighted Average Assumptions) (Details) - Stock Options [Member] - $ / shares |
12 Months Ended | ||
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Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Expected term, years | 4 years 6 months 14 days | 4 years 7 months 18 days | 4 years 7 months 5 days |
| Expected stock price volatility | 28.91% | 29.79% | 26.57% |
| Risk-free interest rate | 1.73% | 1.17% | 1.20% |
| Expected dividend yield | 1.29% | 1.20% | 1.26% |
| Weighted average grant date fair value | $ 13.11 | $ 13.38 | $ 10.36 |
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- Definition 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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition 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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. No definition available.
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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