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Concentrations of Credit Risk (FY) (Details) | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Concentration Risk [Line Items] |  |
Credit extending terms to borrowers | The Bank, as a matter of policy, does not generally extend credit to any single borrower or group of related borrowers in excess of 25% of statutory capital, or approximately $42,325,000. |
Commercial Real Estate [Member] |  |
Concentration Risk [Line Items] |  |
Concentration risk (as a percent) | 56.00% | 61.00%
Loan Portfolio Secured by Real Estate [Member] |  |
Concentration Risk [Line Items] |  |
Concentration risk (as a percent) | 81.00% |

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