Property and Equipment - Additional Information (Detail) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Property, Plant and Equipment [Abstract] | ||
| Fully depreciated computer software and hardware and furniture, fixtures and equipment write-off | $ 2.9 | $ 2.8 |
| X | ||||||||||
- Definition Fully depreciated computer software hardware and furniture fixtures and equipment writeoff. No definition available.
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| X | ||||||||||
- References No definition available.
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