Leases - Schedule of Maturities of Operating and Finance Lease Liabilities (Detail) $ in Thousands	Mar. 31, 2019 USD ($)
Operating Leases
2019 (excluding the three months ended March 31, 2019)	$ 265
2020	409
2021	83
Total lease payments	757
Imputed interest	(68)
Total	689
Finance Lease Liabilities, Payments, Due [Abstract]
2019 (excluding the three months ended March 31, 2019)	24
2020	32
2021	32
Total lease payments	88
Imputed interest	(10)
Total	$ 78