Leases - Summary of Lease Costs (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease costs	$ 1,148	$ 3,456
Short-term lease costs	330	1,547
Variable lease costs	716	2,302
Sublease income	(439)	(439)
Total lease costs	$ 1,755	$ 6,866