Leases - Supplemental balance sheet information related to leases (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Operating Leases:
Operating lease right-of-use assets	$ 14,124	$ 12,521
Operating lease liabilities	$ 14,332	$ 12,690
Weighted Average Remaining Lease Term:
Operating Leases	11 years	11 years
Weighted Average Discount Rate:
Operating Leases	3.10%	3.50%