Other Real Estate Owned - Summary of Activity in Purchased Non-Covered Other Real Estate Owned (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Real Estate Owned, Disclosure of Detailed Components [Abstract]
Beginning balance	$ 15,585us-gaap_OtherRealEstateNonCovered	$ 4,276us-gaap_OtherRealEstateNonCovered	$ 4,276us-gaap_OtherRealEstateNonCovered
Loans transferred to other real estate owned	1,094	68	4,160
Acquired in acquisitions			8,864
Transfer from covered other real estate owned due to loss share expiration			1,226
Net gains (losses) on sale and write-downs	129	49	828
Sales proceeds	(2,990)	(529)	(3,769)
Ending balance	$ 13,818us-gaap_OtherRealEstateNonCovered	$ 3,864us-gaap_OtherRealEstateNonCovered	$ 15,585us-gaap_OtherRealEstateNonCovered

Other Real Estate Non Covered Net Gains Losses On Sale And Write Downs

No definition available.

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- Definition

Other Real Estate Non Covered Transfers Of Loans

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No definition available.

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- Definition

Transfer From Covered Other Real Estate Owned Due To Loss Share Expiration.

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No definition available.

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- Definition

Carrying amount of other real estate not covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

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No definition available.

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- Definition

Additions of other real estate not covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

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No definition available.

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- Definition

Disposals of other real estate not covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

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No definition available.

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Data Type:	xbrli:monetaryItemType
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