Leases - Schedule of Minimum Lease Payments (Detail) $ in Thousands	Mar. 31, 2019 USD ($)
Leases [Abstract]
2019 (remaining 9 months)	$ 4,951
2020	6,382
2021	6,461
2022	6,390
2023	5,158
Total future minimum lease payments	29,342
Less: interest	(5,869)
Total operating lease liabilities	$ 23,473