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Leases - Additional Information (Detail) - USD ($)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Lessee Lease Description [Line Items]    
Total lease expense $ 374,000  
Rent expense   $ 286,000
Lessee, Operating Lease, Existence of Option to Extend [true false] true  
Weighted average remaining operating lease term 3 years 10 months 24 days  
Weighted average discount rate of operating lease 6.40%  
Sublease rental income due in future under non-cancelable subleases $ 2,400,000  
Operating lease liabilities, cash paid 500,000  
Sublease rental income $ 200,000  
Minimum    
Lessee Lease Description [Line Items]    
Remaining lease term 1 year  
Maximum    
Lessee Lease Description [Line Items]    
Remaining lease term 7 years  
Operating leases, options to extend leases term 5 years