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Intangible Assets - Summary of Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified | Sep. 30, 2013 | Dec. 31, 2012 | Sep. 30, 2012
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Schedule Of Intangible Assets [Line Items] |  |  |
Gross Carrying Amount | $ 19,864 |  |
Accumulated Amortization | (9,231) |  |
Net Carrying Amount | 10,633 | 12,083 | 12,630
Core deposit intangibles [Member] |  |  |
Schedule Of Intangible Assets [Line Items] |  |  |
Gross Carrying Amount | 13,473 |  |
Accumulated Amortization | (6,845) |  |
Net Carrying Amount | 6,628 |  |
Customer relationship intangibles [Member] |  |  |
Schedule Of Intangible Assets [Line Items] |  |  |
Gross Carrying Amount | 5,657 |  |
Accumulated Amortization | (2,247) |  |
Net Carrying Amount | 3,410 |  |
Mortgage Servicing Intangibles [Member] |  |  |
Schedule Of Intangible Assets [Line Items] |  |  |
Gross Carrying Amount | 734 |  |
Accumulated Amortization | (139) |  |
Net Carrying Amount | $ 595 |  |

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- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References 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 + Details
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- Definition Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References 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 + Details
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- Definition Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph ((a)(1),(b)) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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