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Employee Benefits Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2018 | Mar. 31, 2018 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Defined Benefit Plan Disclosure |  |  |  |  |
Equity Securities, FV-NI, Unrealized Gain (Loss) | $ (0.1) |  | $ 0.3 |  |
Payment for Other Postretirement Benefits |  |  | 15.7 | $ 20.0 |
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |
Fair value of deferred compensation assets | $ 10.9 |  | 10.9 |  | $ 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 |  | $ 2.9 |  |  |

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- Definition Carrying amount as of the balance sheet date of assets held under deferred compensation agreements. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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