Summary of Lease Costs Recognized Under Topic 842 and Other Information Pertaining to Operating Leases (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Lease cost
Operating lease cost	$ 2,602
Variable lease cost	1,129
Total lease cost	3,731
Other information
Operating lease payments	$ 2,376
Weighted average remaining lease term	6 years 2 months 12 days
Weighted average discount rate	7.50%