Premises and Equipment - Summary 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	$ 31,709us-gaap_Land	$ 36,481us-gaap_Land
Buildings	79,692us-gaap_BuildingsAndImprovementsGross	69,461us-gaap_BuildingsAndImprovementsGross
Furniture and equipment	41,472us-gaap_FurnitureAndFixturesGross	32,705us-gaap_FurnitureAndFixturesGross
Construction in progress	971us-gaap_ConstructionInProgressGross	2,415us-gaap_ConstructionInProgressGross
Property and equipment gross	153,844us-gaap_PropertyPlantAndEquipmentGross	141,062us-gaap_PropertyPlantAndEquipmentGross
Accumulated depreciation	(56,593)	(37,874)
Property and equipment net	$ 97,251us-gaap_PropertyPlantAndEquipmentNet	$ 103,188us-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.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

+ References

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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