Leases - Schedule of Maturity Analysis of Minimum Lease Payment Obligation Under Non-cancellable Operating Leases (Detail) $ in Thousands	Sep. 30, 2019 USD ($)
Lessee Lease Description [Line Items]
Remaining 2019	$ 574
2020	1,768
2021	2,354
2022 and thereafter	530
Total lease payments	5,226
Less: interest	280
Present value of lease liabilities	4,946
Office Leases [Member]
Lessee Lease Description [Line Items]
Remaining 2019	399
2020	1,231
2021	1,727
2022 and thereafter	411
Total lease payments	3,768
Less: interest	220
Present value of lease liabilities	3,548
Leased Vehicles and Office Equipment [Member]
Lessee Lease Description [Line Items]
Remaining 2019	175
2020	537
2021	627
2022 and thereafter	119
Total lease payments	1,458
Less: interest	60
Present value of lease liabilities	$ 1,398