Premises and equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 998,899	$ 960,634
Less - Accumulated depreciation and amortization	605,178	586,479
Subtotal	393,721	374,155
Construction in progress	81,288	33,931
Premises and equipment, net	565,284	498,711
Land
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	90,275	90,625
Building
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 487,053	482,030
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	$ 421,513	388,911
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	$ 90,333	$ 89,693
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