Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 99,032	$ 89,942
Less: accumulated depreciation	44,165	40,022
Premises and equipment, net	54,867	49,920
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	8,301	8,301
Premises and leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	57,131	52,810
Furniture and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	30,853	27,548
Construction in process
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 2,747	$ 1,283