Leases - Schedule of Right-of-Use Assets and Lease Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease - long term right-of-use asset	$ 4,925	$ 0
Current lease liability	1,732	0
Operating lease liability	3,214	$ 0
Total lease liability	$ 4,946