Property and Equipment - Additional Information (Detail) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
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| Property, Plant and Equipment [Abstract] | ||||
| Total depreciation expense recorded | $ 0.1 | $ 0.1 | $ 0.4 | $ 0.4 |
| X | ||||||||||
- Definition The expense recognized in the current period that allocates the cost of nonproduction tangible assets over their useful lives. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- References No definition available.
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