Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 181,814	$ 107,676
Less: Accumulated depreciation	77,349	62,720
Property, plant and equipment, net	104,465	44,956
Depreciation expense of premises and equipment	15,852	8,329	$ 8,557
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	20,209	2,758
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	34,637	6,179
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	62,523	49,704
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	64,445	49,035
Land, Buildings, Leasehold Improvements, Furniture and Equipment
Property, Plant and Equipment [Line Items]
Depreciation expense of premises and equipment	$ 15,000	$ 8,300	$ 8,600

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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The expense recognized in the current period that allocates the cost of nonproduction tangible assets over their useful lives.

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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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