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Stock-Based Compensation (Summary of Unvested Stock Options) (Details) - $ / shares | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Shares |  |  |
Unvested, beginning of period (in shares) | 50,833 |  |
Granted (in shares) | 32,750 | 0 | 50,000
Vested (in shares) | (35,002) |  |
Unvested, end of period (in shares) | 48,581 | 50,833 |
Weighted Average Grant Date Fair Value |  |  |
Unvested, beginning of period (in dollars per share) | $ 12.67 |  |
Granted (in dollars per share) | 11.93 |  | $ 10.33
Vested (in dollars per share) | 13.73 |  |
Unvested, end of period (in dollars per share) | $ 11.41 | $ 12.67 |

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- Definition Employee Service Share-based Compensation, Nonvested Awards, Outstanding, Stock Options, Weighted Average Grant Date Fair Value + References No definition available. + Details
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- Definition Employee Service Share-based Compensation, Nonvested Awards, Vested in Period, Stock Options, Weighted Average Grant Date Fair Value + References No definition available. + Details
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- Definition Gross number of share options (or share units) granted during the period. + 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=6415400&loc=d3e5070-113901 + Details
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