Premises and Equipment - Future Minimum Lease Payments Under Non-cancellable Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Operating Leases, 2021	$ 6,358
Operating Leases, 2022	5,566
Operating Leases, 2023	5,010
Operating Leases, 2024	4,526
Operating Leases, 2025	4,365
Operating Leases, 2026 and thereafter	45,676
Operating Leases, Total lease payments	71,501
Operating Leases, Less: capitalized interest	(15,465)
Operating Leases, Present value of lease liabilities	$ 56,036	$ 56,500
Operating Lease Liability Statement Of Financial Position Extensible List	us-gaap:OtherLiabilities	us-gaap:OtherLiabilities
Finance Leases, 2021	$ 855
Finance Leases, 2022	873
Finance Leases, 2023	885
Finance Leases, 2024	890
Finance Leases, 2025	861
Finance Leases, 2026 and thereafter	3,778
Finance Leases, Total lease payments	8,142
Finance Leases, Less: capitalized interest	(2,962)
Finance Leases, Present value of lease liabilities	5,180	$ 5,600
2021	7,213
2022	6,439
2023	5,895
2024	5,416
2025	5,226
2026 and thereafter	49,454
Total lease payments	79,643
Less: capitalized interest	(18,427)
Present value of lease liabilities	$ 61,216