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Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) | 12 Months Ended |
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Dec. 31, 2017 | Dec. 31, 2016
Summary Of Significant Accounting Policies [Line Items] |  |
Cash equivalents |  | $ 0
Spero Potentiator Australia Pty Limited [Member] | Research and Development Expenses [Member] |  |
Summary Of Significant Accounting Policies [Line Items] |  |
Percentage of refundable tax incentive | 43.50% |

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- Definition Effective Tax Incentive Rate Related To Research And Development + References No definition available. + Details
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- Definition Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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