Stock-based Compensation - Fair-value Methods and Assumptions (Details) - $ / shares |
12 Months Ended | ||
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Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
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| Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] | |||
| Fair value assumptions method used for non-qualified stock options | Black-Scholes-Merton option-pricing model | ||
| Weighted average grant date fair value, per share (in dollars per share) | $ 9.49 | $ 8.13 | $ 6.78 |
| Expected volatility (in percent) | 22.00% | 22.00% | 26.00% |
| Expected lives | 7 years 3 months 18 days | 7 years 3 months 18 days | 7 years 4 months 24 days |
| Risk-free interest rates (in percent) | 1.64% | 2.45% | 1.43% |
| Expected dividend yields (in percent) | 2.52% | 2.72% | 2.56% |
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- References No definition available.
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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 For each plan, identification of the award pricing model or other valuation method used in calculating the weighted average fair values disclosed. The model is also used to calculate the compensation expense that is shown within the balance sheet, income statement, and cash flow. Examples of valuation techniques are lattice models (binomial model), closed-form models (Black-Scholes-Merton formula), and a Monte Carlo simulation technique. Fair value is the amount at which an asset or liability could be bought or incurred or sold or settled in a current transaction between willing parties, that is, other than in a forced or liquidation sale. May include disclosures about the assumptions underlying application of the method selected. 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 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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