Premises and Equipment - Schedule of Premises and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 294,188	$ 228,110
Less accumulated depreciation and amortization	156,920	147,636
Total premises and equipment	137,268	80,474
Land [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	15,446	15,359
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 76,965	78,643
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	$ 52,114	0
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	$ 37,716	27,573
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	$ 71,548	67,735
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	$ 40,399	$ 38,800
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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