Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies - Additional Information (Detail)

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Commitments and Contingencies - Additional Information (Detail)
3 Months Ended 6 Months Ended
Mar. 01, 2018
USD ($)
ft²
Jun. 30, 2019
USD ($)
Jun. 30, 2018
USD ($)
Jun. 30, 2019
USD ($)
Jun. 30, 2018
USD ($)
Jan. 01, 2019
USD ($)
Dec. 31, 2018
USD ($)
Commitment And Contingencies [Line Items]              
Long-term lease agreement, area of office space | ft² 19,275            
Lease term 11 years            
Total lease payments $ 7,300,000 $ 55,000   $ 219,000      
Lessee, operating lease, existence of option to extend true            
Renewal term 5 years            
Renewal term, description The Company has the option to renew for two consecutive five-year periods from the end of the first term and the Company is not reasonably certain that the option to renew the Lease will be exercised. Under the Lease, the Company must furnish a security deposit in the form of a standby letter of credit in the amount of $0.3 million, which will be reduced by fifty-five thousand dollars every two years for ten years after the commencement of the lease            
Security deposit in the form of a standby letter of credit $ 300,000            
Decrease in security deposit $ 55,000            
Operating lease right-of-use asset   3,284,000   3,284,000   $ 3,365,000 $ 0
Operating lease liability   $ 3,401,000   3,401,000   $ 3,368,000  
Maximum              
Commitment And Contingencies [Line Items]              
Milestone payments from the Company       $ 19,000,000      
Jersey City, New Jersey              
Commitment And Contingencies [Line Items]              
Rent expense     $ 100,000   $ 100,000