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Loans - Troubled Debt Restructurings (Detail) - USD ($) $ in Thousands | 9 Months Ended
--- | ---
Sep. 30, 2015 | Sep. 30, 2014
Financing Receivable, Modifications [Line Items] |  |
Balance at time of restructuring | $ 709 | $ 6,874
Balance at period end | 554 | 6,524
Commercial and industrial, Energy [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Balance at time of restructuring | 0 | 0
Balance at period end | 0 | 0
Commercial and industrial, Other commercial [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Balance at time of restructuring | 709 | 3,752
Balance at period end | 554 | 3,516
Commercial real estate, Buildings, land and other [Member] |  |
Financing Receivable, Modifications [Line Items] |  |
Balance at time of restructuring | 0 | 3,122
Balance at period end | $ 0 | $ 3,008

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- Definition Post-modification amount of investment in financing receivables modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524 + Details
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