Property and Equipment - Additional Information (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
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| Property Plant And Equipment [Abstract] | |||
| Depreciation and amortization | $ 0.2 | $ 0.3 | $ 0.4 |
| X | ||||||||||
- Definition The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- References No definition available.
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