Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands |
6 Months Ended | 12 Months Ended | |
|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Dec. 31, 2017 |
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| Property Plant And Equipment [Abstract] | |||
| Depreciation expense | $ 64 | $ 14 | $ 65 |
| X | ||||||||||
- Definition The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- References No definition available.
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