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Employee Benefits, Defined Benefit Plans Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | ---
Mar. 31, 2015 | Jun. 30, 2015 | Jun. 30, 2016 | 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
Non-cash loss | $ 307.8 |  |  |
Income tax benefit | $ 184.4 | $ 184.4 |  |
Accrued Veba contingent contribution - total |  |  | $ 29.9 |
Salaried VEBA |  |  |  |
VEBA Postretirement Medical Obligations |  |  |  |
Accrued annual contribution to VEBAs |  |  |  | $ 2.8

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