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Fair Value Measurements (Details Textual) - USD ($) | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Fair Value Disclosures [Abstract] |  |  |
Fair value measurement transfers from one level to another | $ 0 | $ 0 | $ 0
Fair Value, Option, Changes in Fair Value, Gain (Loss) | $ 994,000 | $ 0 | $ 0

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- Definition Fair Value Measurement Transfers From One Level To Another + References No definition available. + Details
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- Definition For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 30 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612 + Details
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