Leases - Summary of Maturity of Lease Liability (Detail) $ in Thousands	Jun. 30, 2019 USD ($)
Leases [Abstract]
Remainder of 2019	$ 1,392
2020	4,024
2021	4,553
2022	4,713
2023	1,188
Total lease payments	15,870
Less imputed interests	(2,662)
Total lease liability	$ 13,208