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Loans and Allowance for Credit Losses - Troubled Debt Restructured Loans and Commitments (Detail) - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
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Financing Receivable, Troubled Debt Restructurings [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring | $ 14,994 | $ 20,518
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend | 323 | 1,087
Letter of Credit [Member] |  |
Financing Receivable, Troubled Debt Restructurings [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend | 60 | 60
Unused lines of Credit [Member] |  |
Financing Receivable, Troubled Debt Restructurings [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend | 263 | 1,027
Accrual Loans [Member] [Member] |  |
Financing Receivable, Troubled Debt Restructurings [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring | 9,120 | 8,757
Non Accrual Loans [Member] |  |
Financing Receivable, Troubled Debt Restructurings [Line Items] |  |
Financing Receivable, Troubled Debt Restructuring | $ 5,874 | $ 11,761

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- Definition Amount of financing receivable modified as troubled debt restructuring. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=118939409&loc=d3e18845-111554 + Details
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- Definition Amount of unfunded portion of contractual agreement to lend funds to borrower for financing receivable modified as troubled debt restructuring. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118939409&loc=d3e18794-111554 + Details
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