Premises and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Operating Lease, Liability	$ 52,894
Operating Leases, Rent Expense, Contingent Rentals	4,900	$ 4,100	$ 2,700
Premises and Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation included in noninterest expense	10,500	$ 9,500	$ 9,000
Property Subject to Operating Lease [Member]
Property, Plant and Equipment [Line Items]
Depreciation included in noninterest expense	3,500
Accounting Standards Update 2016-02 [Member]
Property, Plant and Equipment [Line Items]
Operating Lease, Right-of-Use Asset	38,500
Operating Lease, Liability	$ 41,800