Premises and Equipment - Schedule of Premises and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property Plant and Equipment Useful Life and Values [Abstract]
Land	$ 75,916us-gaap_Land	$ 77,113us-gaap_Land
Buildings	232,727us-gaap_BuildingsAndImprovementsGross	217,469us-gaap_BuildingsAndImprovementsGross
Furniture, fixtures and equipment	128,388us-gaap_FurnitureAndFixturesGross	110,663us-gaap_FurnitureAndFixturesGross
Total premises and equipment	437,031us-gaap_PropertyPlantAndEquipmentGross	405,245us-gaap_PropertyPlantAndEquipmentGross
Accumulated depreciation	(129,872)	(117,735)
Total premises and equipment, net	$ 307,159us-gaap_PropertyPlantAndEquipmentNet	$ 287,510us-gaap_PropertyPlantAndEquipmentNet

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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 of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

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Amount before accumulated depreciation of equipment commonly used in offices and stores that have no permanent connection to the structure of a building or utilities. Examples include, but are not limited to, desks, chairs, tables, and bookcases.

+ References

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Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

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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.

+ References

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