Premises and Equipment - Schedule of Premises and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 291,264	$ 294,188
Less accumulated depreciation and amortization	165,747	156,920
Total premises and equipment	125,517	137,268
Land [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	15,441	15,446
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 77,003	76,965
Buildings and improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Buildings and improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	50 years
Property Subject to Operating Lease [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 48,642	52,114
Property Subject to Operating Lease [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	1 year
Property Subject to Operating Lease [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	25 years
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 35,347	37,716
Leasehold improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Leasehold improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	40 years
Furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 73,150	71,548
Furniture and equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Furniture and equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	7 years
Software [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 41,681	$ 40,399
Software [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Software [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	7 years

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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