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Loans and Allowance for Credit Losses - Troubled Debt Restructured Loans and Commitments (Detail) - USD ($) $ in Thousands | Sep. 30, 2017 | Dec. 31, 2016
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Financing Receivable, Troubled Debt Restructurings [Line Items] |  |
Financing Receivable, Modifications, Recorded Investment | $ 23,859 | $ 25,359
Loans and Leases Receivable, Impaired, Commitment to Lend | 301 | 358
Letter of Credit [Member] |  |
Financing Receivable, Troubled Debt Restructurings [Line Items] |  |
Loans and Leases Receivable, Impaired, Commitment to Lend | 60 | 0
Unused lines of Credit [Member] |  |
Financing Receivable, Troubled Debt Restructurings [Line Items] |  |
Loans and Leases Receivable, Impaired, Commitment to Lend | 241 | 358
Accrual Loans [Member] [Member] |  |
Financing Receivable, Troubled Debt Restructurings [Line Items] |  |
Financing Receivable, Modifications, Recorded Investment | 12,451 | 13,790
Non Accrual Loans [Member] |  |
Financing Receivable, Troubled Debt Restructurings [Line Items] |  |
Financing Receivable, Modifications, Recorded Investment | $ 11,408 | $ 11,569

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- Definition Financing Receivable, Troubled Debt Restructurings [Line Items] [Line Items] + References No definition available. + Details
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- Definition The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Recorded Investment -URI http://asc.fasb.org/extlink&oid=65880944 + Details
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- Definition Reflects the unfunded portion of contractual agreements to lend funds to borrowers for loans whose terms have been modified by troubled debt restructuring. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18794-111554 + Details
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