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Securities - Narrative (Details) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2019 USD ($) investment | Mar. 31, 2018 USD ($) | Dec. 31, 2018 USD ($)
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Proceeds from sale of available-for-sale securities | $ | $ 0 | $ 0 |
Realized gain (loss) | $ | 0 | $ 0 |
Proceeds from call of debt security | $ | 5,000,000 |  |
Collateral Pledged [Member] |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Restricted securities | $ | $ 108,000,000 |  | $ 97,200,000
US Government-sponsored Enterprises Debt Securities [Member] |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Number of positions | investment | 8 |  |
Municipal securities [Member] |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Number of positions | investment | 8 |  |
Other debt securities [Member] |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Number of positions | investment | 1 |  |
Mortgage-backed securities [Member] |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Number of positions | investment | 68 |  |

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