Premises and Equipment - Bank Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Gross	$ 302,152	$ 262,402
Accumulated depreciation	(92,984)	(79,148)
Net	209,168	183,254
Premises
Property, Plant and Equipment [Line Items]
Gross	218,730	193,173
Leasehold improvements
Property, Plant and Equipment [Line Items]
Gross	10,241	7,736
Furniture and equipment
Property, Plant and Equipment [Line Items]
Gross	52,043	45,625
Computer equipment
Property, Plant and Equipment [Line Items]
Gross	20,972	15,686
Autos
Property, Plant and Equipment [Line Items]
Gross	$ 166	$ 182

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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