Goodwill and Other Intangible Assets (Schedule of Other Intangible Assets) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 50,762	$ 43,971
Accumulated Amortization	(38,637)	(37,626)
Net Intangible Assets	12,125us-gaap_FiniteLivedIntangibleAssetsNet	6,345us-gaap_FiniteLivedIntangibleAssetsNet
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	44,266	34,966
Accumulated Amortization	(34,591)	(31,961)
Net Intangible Assets	9,675	3,005
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	5,771	7,870
Accumulated Amortization	(3,643)	(5,042)
Net Intangible Assets	2,128	2,828
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	725	1,135
Accumulated Amortization	(403)	(623)
Net Intangible Assets	$ 322	$ 512

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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