Leases - Schedule of 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	$ 77,482	$ 95,477
Operating lease liabilities	88,552	99,500
Finance Leases
Premises and equipment, net	11,662	7,170
Other borrowings	$ 12,062	$ 7,406
Weighted-Average Remaining Lease Term (in Years)
Operating leases	10 years 7 months 6 days	10 years 7 months 6 days
Finance leases	10 years 6 months	11 years 3 months 18 days
Weighted-Average Discount Rate
Operating leases	3.40%	3.45%
Finance leases	3.45%	4.43%
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentNet	us-gaap:PropertyPlantAndEquipmentNet
Finance Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherBorrowings	us-gaap:OtherBorrowings