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Loans and Allowance for Loan Losses - Troubled Debt Restructuring by Class (Details) | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2018 USD ($) loan | Dec. 31, 2017 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Number of loans removed from TDR designation | loan |  | 0
Recorded investment of loans removed from TDR resignation | $ 247,000 |
Recorded investment in Troubled Debt Restructurings | $ 15,213,000 | $ 16,520,000
TDR loans on non-accrual status, quantity | loan | 2 |
TDR loans on non-accrual status | $ 68,000 | $ 0
Acquired loans on TDR status | loan | 0 | 0
Commercial loans | Commercial and industrial |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Recorded investment in Troubled Debt Restructurings | $ 1,763,000 | $ 2,165,000
Commercial real estate loans | Commercial real estate, owner-occupied |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Recorded investment in Troubled Debt Restructurings | 6,997,000 | 6,999,000
Commercial real estate loans | Commercial real estate, investor |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Recorded investment in Troubled Debt Restructurings | 1,831,000 | 2,171,000
Commercial real estate loans | Construction |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Recorded investment in Troubled Debt Restructurings | $ 2,690,000 | 2,969,000
Residential loans | Home equity |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Number of loans removed from TDR designation | loan | 1 |
Recorded investment in Troubled Debt Restructurings | $ 251,000 | 347,000
Residential loans | Other residential |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Number of loans removed from TDR designation | loan | 1 |
Recorded investment in Troubled Debt Restructurings | $ 986,000 | 1,148,000
Consumer loans | Installment and other consumer |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Recorded investment in Troubled Debt Restructurings | $ 695,000 | $ 721,000

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