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Operating Leases - Narrative (Detail) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2018 ft² location | Dec. 31, 2017 USD ($)
Leases [Abstract] |  |
Area of operating lease | ft² | 37,829 |
Number of office space locations | location | 1 |
Operating lease expense excluding rent | $ |  | $ 0.4

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- Definition Lessee Leasing Agreements, Operating Leases, Area under Lease + References No definition available. + Details
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- Definition Lessee Leasing Agreements, Operating Leases, locations + References No definition available. + Details
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- Definition Operating Lease Expense Excluding Rent + References No definition available. + Details
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- References No definition available. + Details
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