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Securities - Narrative (Q2) (Details) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2018 USD ($) investment | Jun. 30, 2017 USD ($) | Jun. 30, 2018 USD ($) investment | Jun. 30, 2017 USD ($) | Dec. 31, 2017 USD ($)
Loans and Leases Receivable Disclosure [Line Items] |  |  |  |  |
Proceeds from sale of available-for-sale securities | $ | $ 0 | $ 0 | $ 0 | $ 0 |
Loss from redemption of securities | $ | 1,200 |  | 1,200 | $ 0 |
Collateral Pledged [Member] |  |  |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |  |  |
Restricted securities | $ | $ 113,500,000 |  | $ 113,500,000 |  | $ 97,200,000
Mortgage-backed securities [Member] |  |  |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |  |  |
Number of positions | 65 |  | 65 |  |
US Government-sponsored Enterprises Debt Securities [Member] |  |  |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |  |  |
Number of positions | 8 |  | 8 |  |
Municipal securities [Member] |  |  |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |  |  |
Number of positions | 21 |  | 21 |  |
Other debt securities [Member] |  |  |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |  |  |
Number of positions | 1 |  | 1 |  |

X
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