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Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | --- | ---
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Related allowance | $ 6.8 | $ 10.8 | $ 14.0
Fair Value Measured on a Non-recurring Basis |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Impaired loans | (12.2) | (22.2) |
Fair Value Measured on a Non-recurring Basis | Significant Unobservable Inputs (Level 3) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Impaired loans | 24.1 | 32.6 |
Related allowance | 6.8 | 10.8 |
Partial loan charge-off | 5.4 | 11.4 |
Carrying Amount | Fair Value Measured on a Non-recurring Basis | Significant Unobservable Inputs (Level 3) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Impaired loans | 36.3 | 54.8 |
Assets Held-for-sale, Long Lived, Fair Value Disclosure | 5.4 | 0.8 |
Changes Measurement [Member] | Fair Value Measured on a Non-recurring Basis |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Assets Held-for-sale, Long Lived, Fair Value Disclosure | 0.5 | 0.0 |
Estimated Fair Value | Fair Value Measured on a Non-recurring Basis |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Impaired loans | 24.1 |  |
Assets Held-for-sale, Long Lived, Fair Value Disclosure | 4.9 | 0.8 |
Estimated Fair Value | Fair Value Measured on a Non-recurring Basis | Significant Unobservable Inputs (Level 3) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Impaired loans | $ 24.1 | $ 32.6 |

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