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Borrowings (Narrative) (Details) - USD ($) |  | 12 Months Ended |  |
--- | --- | --- | --- | ---
Apr. 15, 2015 | Dec. 31, 2016 | Dec. 31, 2015 | Jun. 30, 2015
Short-term Debt [Line Items] |  |  |  |
Short-term borrowings, weighted average rate |  | 0.76% | 0.53% |
Short-term borrowings |  | $ 331,500,000 | $ 293,100,000 |
Subordinated Notes Due April 15, 2030 [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Cost related to issuance of debt |  | 1,100,000 |  |
Proceeds from issuance of debt, net |  | $ 38,900,000 |  |
Principal amount | $ 40,000,000 |  |  | $ 40,000,000
Interest rate | 6.00% |  |  |
Number of years at stated rate |  | 10 years |  |
Debt issuance cost amortization period |  | 15 years |  |
Federal Home Loan Bank Advances [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Short-term borrowings |  | $ 331,500,000 | 293,100,000 |
Federal Home Loan Bank Overnight Borrowings [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Short-term borrowings |  | 171,500,000 | 116,800,000 |
Federal Home Loan Borrowings Short Term Advances [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Short-term borrowings |  | $ 160,000,000 | $ 176,300,000 |
LIBOR [Member] | Subordinated Notes Due April 15, 2030 [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Spread on variable rate | 3.944% |  |  |

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