Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Accrued Liabilities And Other Liabilities [Abstract]
Accrued compensation	$ 1,370	$ 1,837
Accrued contracted research and development costs	3,155	2,552
Accrued professional and consulting fees	623	672
Accrued other and other current liabilities	75	159
Total accrued and other current liabilities	$ 5,223	$ 5,220

Amount of expenses incurred but not yet paid classified as other, due within one year or the normal operating cycle, if longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 210
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-Section 45
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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