Borrowed Funds (Summary of Short Term Borrowings) (Details) - USD ($) $ in Thousands |
9 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2017 |
Dec. 31, 2016 |
|
| Outstanding at end of period | $ 45,815 | $ 36,000 |
| Weighted average interest rate | 0.11% | 0.16% |
| Maximum amount outstanding as of any month end | $ 45,815 | $ 39,456 |
| Average amount outstanding | $ 32,523 | $ 30,899 |
| Securities Sold under Agreements to Repurchase [Member] | ||
| Weighted average interest rate | 0.15% | 0.19% |