Share Based Award ESPP Table (Details) - Employee Stock [Member] - USD ($) $ in Thousands |
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] | |||
Stock Issued During Period, Shares, Employee Stock Purchase Plans | 23,426 | 31,227 | 34,299 |
Stock Issued During Period, Value, Employee Stock Purchase Plan | $ 986 | $ 955 | $ 1,382 |
Fair Value Assumptions, Expected Term | 6 months | 6 months | 6 months |
Expected stock price volatility | 28.10% | 32.50% | 27.00% |
Risk-Free Interest Rate | 0.60% | 0.30% | 0.60% |
Expected Dividend Yield | 0.00% | 0.00% | 0.00% |
X | ||||||||||
- Definition Period the instrument, asset or liability is expected to be outstanding, 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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X | ||||||||||
- 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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X | ||||||||||
- 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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X | ||||||||||
- 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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X | ||||||||||
- 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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X | ||||||||||
- Definition Number of shares issued during the period as a result of an employee stock purchase plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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X | ||||||||||
- Definition Aggregate change in value for stock issued during the period as a result of employee stock purchase plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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