Commitments and Contingencies - Schedule of Future Minimum Lease Payments under Non-cancellable Operating Leases, Reconciliation of Undiscounted Cash Flows to the Operating Lease Liability (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Operating Lease Liabilities, Payments Due [Abstract]
2020 (Excluding the six months ended June 30, 2020)	$ 625
2021	1,264
2022	1,288
2023	1,311
Total future minimum lease payments, undiscounted	4,488
Less imputed interest	(523)
Operating lease liability	3,965
Operating lease liability reported as of June 30, 2020:
Operating lease liability - current	1,006	$ 967
Operating lease liability - non-current	2,959	$ 3,352
Total	$ 3,965