Leases - Summary of Lease Costs and Supplemental Cash Flow Information of Operating Leases (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Operating lease cost	$ 697	$ 1,398
Variable lease cost	138	298
Total lease cost	835	1,696
Cash paid for amounts included in operating lease liabilities	684	1,395
Right-of-use assets acquired through operating lease liabilities	$ (371)	$ (335)