Loans - Composition of TDRs by Accrual and Nonaccrual Status (Details) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Accounts Notes And Loans Receivable [Line Items] | ||
| Troubled Debt Restructurings, Nonaccrual | $ 11,359 | $ 8,238 |
| Troubled Debt Restructurings, Total | 4,500 | 3,400 |
| Commercial and Industrial Loans | ||
| Accounts Notes And Loans Receivable [Line Items] | ||
| Troubled Debt Restructurings, Nonaccrual | 9,617 | 3,359 |
| Principal Reduction and Extended Maturity | Commercial and Industrial Loans | ||
| Accounts Notes And Loans Receivable [Line Items] | ||
| Troubled Debt Restructurings, Accrual | 195 | 317 |
| Troubled Debt Restructurings, Nonaccrual | 4,296 | 3,109 |
| Troubled Debt Restructurings, Total | $ 4,491 | $ 3,426 |