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Loans and Related Allowance for Loan Losses (Narrative) (Details) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2017 USD ($) contract | Mar. 31, 2016 USD ($) contract | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Financing Receivable, Modifications [Line Items] |  |  |  |
Commercial amount benchmark minimum for internal annual review | $ 500,000 |  |  |
Commercial amount benchmark minimum for annual review by independent reviewer | 1,000,000 |  |  |
Commercial amount benchmark minimum criticized relationships for annual review by independent reviewer | 500,000 |  |  |
Nonaccrual loans | 10,893,000 |  | $ 13,946,000 |
Paydown of large relationship | 2,500,000 |  |  |
Reduction of the ALL resulting from change in evaluation method of loans |  | $ 2,387 |  |
Loans in process of foreclosure | $ 300,000 |  | $ 500,000 |
Accruing loans past due 30 days or greater as percent of loan portfolio | 0.46% |  | 0.67% |
Total allowance for loan losses | $ 11,583,000 | $ 12,256,000 | $ 9,918,000 | $ 11,922,000
Partial Charge Off [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Nonaccrual loans | $ 7,800,000 |  | 11,100,000 |
New TDR [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Financing receivable, modifications, number of contracts | contract | 0 | 2 |  |
Pre Existing TDR Loans Remodified After Maturity [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Financing receivable, modifications, number of contracts | contract | 2 | 1 |  |
Commercial real estate- non owner-occupied [Member] |  |  |  |
Financing Receivable, Modifications [Line Items] |  |  |  |
Nonaccrual loans | $ 5,478,000 |  | $ 6,381,000 |

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