Allowance for Loan Losses - Weighted Average Annualized Balance of Recorded Investment and Interest Income on Impaired Loans (Details) - USD ($) $ in Thousands |
9 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2017 |
Dec. 31, 2016 |
|
| Financing Receivable Modifications [Line Items] | ||
| Average Recorded Investment | $ 8,420 | $ 5,899 |
| Interest Income after Impairment | 49 | 51 |
| Residential Properties | ||
| Financing Receivable Modifications [Line Items] | ||
| Average Recorded Investment | 2,427 | 1,970 |
| Interest Income after Impairment | 20 | 14 |
| Commercial Real Estate | ||
| Financing Receivable Modifications [Line Items] | ||
| Average Recorded Investment | 2,201 | 2,252 |
| Interest Income after Impairment | 16 | 17 |
| Commercial and Industrial Loans | ||
| Financing Receivable Modifications [Line Items] | ||
| Average Recorded Investment | 3,792 | 1,673 |
| Interest Income after Impairment | $ 13 | 20 |
| Consumer Loans | ||
| Financing Receivable Modifications [Line Items] | ||
| Average Recorded Investment | $ 4 |