Leases - Schedule of Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Operating Leases
Operating lease right-of-use assets	$ 102,976	$ 0	$ 0
Operating lease liabilities	107,272	$ 0	$ 0
Finance Leases
Premises and equipment, net	7,337
Other borrowings	$ 7,527
Weighted-Average Remaining Lease Term (in Years)
Operating leases	10 years 9 months 18 days
Finance leases	11 years 6 months
Weighted-Average Discount Rate
Operating leases	3.45%
Finance leases	4.43%