Premises and equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 960,634	$ 929,891
Less - Accumulated depreciation and amortization	586,479	559,234
Subtotal	374,155	370,657
Construction in progress	33,931	29,337
Premises and equipment, net	498,711	494,240
Land
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	90,625	94,246
Building
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 482,030	468,293
Building | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	50 years
Building | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 388,911	374,192
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 89,693	$ 87,406
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years