Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Land	$ 10,356	$ 10,471
Buildings and building improvements	42,481	47,006
Leasehold improvements	14,260	12,880
Furniture, fixtures and equipment	31,728	27,858
Premises and equipment, gross	98,825	98,215
Less accumulated depreciation and amortization	51,217	49,040
Premises and equipment	$ 47,608	$ 49,175
Buildings and building improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	10 years
Buildings and building improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	50 years
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	10 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	25 years
Furniture, fixtures and equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Furniture, fixtures and equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	30 years