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Allowance for Loan Losses - Recorded Investment in Consumer Loan Classes by Performing and Nonperforming Status (Detail) - Consumer - USD ($) $ in Thousands | Sep. 30, 2016 | Dec. 31, 2015
--- | --- | ---
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 1,244,649 | $ 1,190,735
Percentage of Total | 100.00% | 100.00%
Performing Financing Receivable |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 1,230,250 | $ 1,182,104
Percentage of Total | 98.80% | 99.30%
Nonperforming Financing Receivable |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 14,399 | $ 8,631
Percentage of Total | 1.20% | 0.70%
Residential Mortgage |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 692,574 | $ 639,372
Percentage of Total | 100.00% | 100.00%
Residential Mortgage | Performing Financing Receivable |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 681,174 | $ 633,743
Percentage of Total | 98.40% | 99.10%
Residential Mortgage | Nonperforming Financing Receivable |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 11,400 | $ 5,629
Percentage of Total | 1.60% | 0.90%
Home Equity |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 483,935 | $ 470,845
Percentage of Total | 100.00% | 100.00%
Home Equity | Performing Financing Receivable |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 480,980 | $ 467,943
Percentage of Total | 99.40% | 99.40%
Home Equity | Nonperforming Financing Receivable |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 2,955 | $ 2,902
Percentage of Total | 0.60% | 0.60%
Installment and Other Consumer |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 62,288 | $ 73,939
Percentage of Total | 100.00% | 100.00%
Installment and Other Consumer | Performing Financing Receivable |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 62,244 | $ 73,839
Percentage of Total | 99.90% | 99.80%
Installment and Other Consumer | Nonperforming Financing Receivable |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 44 | $ 100
Percentage of Total | 0.10% | 0.20%
Consumer Construction |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 5,852 | $ 6,579
Percentage of Total | 100.00% | 100.00%
Consumer Construction | Performing Financing Receivable |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 5,852 | $ 6,579
Percentage of Total | 100.00% | 100.00%
Consumer Construction | Nonperforming Financing Receivable |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 0 | $ 0
Percentage of Total | 0.00% | 0.00%

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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 Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4428-111522 + Details
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