Leases - Summary of Components of Lease Costs (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Finance lease costs:
Amortization of right-of-use assets	$ 244	$ 728
Interest on finance lease liabilities	233	687
Operating lease costs	538	1,618
Short-term lease costs	61	195
Variable lease costs	173	501
Total lease costs	$ 1,249	$ 3,729