Commitments and Contingencies - Summary of Lease Costs and Supplemental Cash Flow Information of Operating Leases (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating lease cost	$ 700
Variable lease cost	161
Total lease cost	861
Cash paid for amounts included in the measurement of operating lease liabilities	711
Right-of-use assets acquired through operating lease liabilities	$ 36