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Loans - Narrative (Details) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2017 USD ($) Contract | Dec. 31, 2016 USD ($) Contract | Dec. 31, 2013 Contract
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Period for order of valuations (at least) | 18 months |  |
Number of troubled debt restructured loan paid off |  | 1 |
Number of loans which has periodic late payments | 1 |  |
Number of loans classified as troubled debt restructured loans with active forbearance agreements | 2 |  |
Number of forbearance agreements negotiated |  |  | 1
Consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings are in process | $ | $ 427 | $ 471 |
Residential mortgage and commercial loans |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Threshold period past due to discontinue accrual interest on financing receivable | 90 days |  |
Consumer |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Threshold period past due for write-off of financing receivable (no later than) | 120 days |  |
Commercial real estate |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Period of financing receivable, updated valuation on real estate secured loans, 90 days past due | 90 days |  |
Number of Previous Months with No Updated Valuation Completed for Corporation to Update Valuation | 12 months |  |
Impaired financing receivable, valuation on real estate collateralized loans | 30 days |  |
Residential mortgage |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Financing receivable, loan to value ratio of appraised value of property | 80.00% |  |
Entity Loan Modification Program |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Proceeds from paid off troubled debt restructured loans | $ |  | $ 74 |
Maximum | Commercial real estate |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Financing receivable, term | 20 years |  |
Financing receivable, loan to value ratio of appraised value of property | 80.00% |  |
Maximum | Residential mortgage |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Financing receivable, term | 30 years |  |
Maximum | Home equity lines of credit |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Financing receivable, term | 20 years |  |
Financing receivable, loan to value ratio of appraised value of property | 90.00% |  |

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