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Stockholders' Equity (Fair Value Assumptions For Options Granted) (Details) | 12 Months Ended
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Dec. 31, 2017 $ / shares
January, 3, 2017 [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Risk-free Interest Rate | 1.90%
Expected Life of Option in Years | 5 years
Expected Dividend Yield | 2.60%
Expected Stock Volatility | 24.49%
Estimated Fair Value of Stock Option (in dollars per share) | $ 8.40
April 19, 2016 [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Risk-free Interest Rate | 1.30%
Expected Life of Option in Years | 5 years
Expected Dividend Yield | 2.60%
Expected Stock Volatility | 26.34%
Estimated Fair Value of Stock Option (in dollars per share) | $ 8.18
April 21, 2015 [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Risk-free Interest Rate | 1.30%
Expected Life of Option in Years | 5 years
Expected Dividend Yield | 2.70%
Expected Stock Volatility | 26.84%
Estimated Fair Value of Stock Option (in dollars per share) | $ 7.35
April 22, 2014 [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Risk-free Interest Rate | 1.80%
Expected Life of Option in Years | 5 years
Expected Dividend Yield | 2.00%
Expected Stock Volatility | 28.55%
Estimated Fair Value of Stock Option (in dollars per share) | $ 9.57
April 16, 2013 [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Risk-free Interest Rate | 0.70%
Expected Life of Option in Years | 5 years
Expected Dividend Yield | 1.60%
Expected Stock Volatility | 37.42%
Estimated Fair Value of Stock Option (in dollars per share) | $ 12.66
April 17, 2012 [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Risk-free Interest Rate | 0.90%
Expected Life of Option in Years | 5 years
Expected Dividend Yield | 1.40%
Expected Stock Volatility | 39.25%
Estimated Fair Value of Stock Option (in dollars per share) | $ 13.69
April 19, 2011 [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Risk-free Interest Rate | 2.10%
Expected Life of Option in Years | 5 years
Expected Dividend Yield | 1.60%
Expected Stock Volatility | 39.33%
Estimated Fair Value of Stock Option (in dollars per share) | $ 11.20
April 20, 2010 [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Risk-free Interest Rate | 2.60%
Expected Life of Option in Years | 5 years
Expected Dividend Yield | 1.50%
Expected Stock Volatility | 39.10%
Estimated Fair Value of Stock Option (in dollars per share) | $ 8.14
April 21, 2009 [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Risk-free Interest Rate | 1.90%
Expected Life of Option in Years | 5 years
Expected Dividend Yield | 1.00%
Expected Stock Volatility | 38.80%
Estimated Fair Value of Stock Option (in dollars per share) | $ 3.64

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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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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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. + Details
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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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(i) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.D.2) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 + Details
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