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Employee Benefits Narrative (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2019 | Mar. 31, 2018 | Dec. 31, 2018
Defined Benefit Plan Disclosure |  |  |
Equity Securities, FV-NI, Unrealized Gain (Loss) | $ 0.5 |  |
Payment for Other Postretirement Benefits | 2.1 | $ 15.7 |
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring |  |  |
Defined Benefit Plan Disclosure |  |  |
Fair value of deferred compensation assets | 11.0 |  | $ 9.8
Postretirement Health Coverage | Union VEBA |  |  |
Defined Benefit Plan Disclosure |  |  |
Maximum contribution threshold |  | $ 12.8 |
Postretirement Health Coverage | Salaried VEBA |  |  |
Defined Benefit Plan Disclosure |  |  |
Maximum contribution threshold | 2.9 |  |
Payment for Other Postretirement Benefits | $ 2.1 |  |

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