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Employee Benefits, Defined Benefit Plans Narrative (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2016 | Mar. 31, 2015 | Dec. 31, 2015
VEBA Postretirement Medical Obligations |  |  |
Accrued annual contribution to VEBAs | $ 0.0 |  | $ 19.6
VEBAs |  |  |
VEBA Postretirement Medical Obligations |  |  |
Accrued annual contribution to VEBAs |  |  | 19.5
Union VEBA |  |  |
VEBA Postretirement Medical Obligations |  |  |
Accrued annual contribution to VEBAs |  |  | 16.7
Accrued Veba contingent contribution - total | 29.9 |  |
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments |  | $ 307.8 |
Income Tax Expense (Benefit) | $ 184.4 | $ 184.4 |
Salaried VEBA |  |  |
VEBA Postretirement Medical Obligations |  |  |
Accrued annual contribution to VEBAs |  |  | $ 2.8

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