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Loans and Allowance for Loan Losses - Allowance for Loan Losses Outstanding by Impairment Methodology (Detail) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually evaluated for impairment | $ 9,578 | $ 9,876
Collectively evaluated for impairment | 42,297 | 41,790
Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually evaluated for impairment | 891 | 656
Collectively evaluated for impairment | 5,535 | 5,539
Real Estate [Member] | Non-residential Real Estate Other [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually evaluated for impairment | 978 | 751
Collectively evaluated for impairment | 9,670 | 9,768
Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually evaluated for impairment | 570 | 483
Collectively evaluated for impairment | 2,741 | 2,743
Real Estate [Member] | Residential Real Estate All Other [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually evaluated for impairment | 3,263 | 2,761
Collectively evaluated for impairment | 7,158 | 6,911
Commercial and Financial [Member] | Non-consumer Non-real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually evaluated for impairment | 3,486 | 4,651
Collectively evaluated for impairment | 10,910 | 10,683
Consumer Non-real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually evaluated for impairment | 346 | 429
Collectively evaluated for impairment | 2,567 | 2,364
Other Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually evaluated for impairment | 44 | 133
Collectively evaluated for impairment | 2,378 | 2,348
Acquired Loans [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Individually evaluated for impairment |  | 12
Collectively evaluated for impairment | $ 1,338 | $ 1,434

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 + Details
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- Definition Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 + Details
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