Premises and Equipment - Components and Depreciation and Amortization Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of premises and equipment
Premises and equipment	$ 547,071	$ 522,813
Less: Accumulated depreciation and amortization	230,186	217,817
Net book value	316,885	304,996
Depreciation and amortization expenses	14,522	15,303	$ 15,278
Occupancy
Components of premises and equipment
Depreciation and amortization expenses	9,037	8,815	8,852
Equipment
Components of premises and equipment
Depreciation and amortization expenses	5,485	6,488	$ 6,426
Buildings
Components of premises and equipment
Premises and equipment	289,271	280,853
Less: Accumulated depreciation and amortization	141,300	133,700
Furniture and equipment
Components of premises and equipment
Premises and equipment	86,485	81,342
Land
Components of premises and equipment
Premises and equipment	106,487	105,302
Leasehold improvements
Components of premises and equipment
Premises and equipment	$ 64,828	$ 55,316

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 aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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