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Employee Benefits - Benefit Obligations and Funded Status of Pension Plans, OPEB and Salaried VEBAs (Parenthetical) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items] |  |
Actuarial gain (loss) due to change in discount rate | $ 8.0 |
Actuarial gain (loss) due to changes in census data | (0.9) | $ 0.3
Long term Liabilities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | 4.9 | 10.5
Other Assets |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | 1.0 |
Other Postretirement Benefits Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Actuarial gain (loss) due to change in discount rate | 20.4 | (3.2)
Actuarial gain (loss) due to changes in census data | 0.7 | 0.6
Actuarial gain (loss) due to change in trend rate | (0.7) |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | (66.4) | (83.5)
Other Postretirement Benefits Plan | Long term Liabilities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | 64.4 | 81.9
Other Postretirement Benefits Plan | Accrued Salaries and Wages and Related Expenses |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | 2.0 |
Other Postretirement Benefits Plan | Pension and Other Postretirement Benefits |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Defined Benefit Plan, Funded (Unfunded) Status of Plan |  | 1.6
Salaried VEBA |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Actuarial gain (loss) due to change in discount rate | 12.6 | 3.0
Actuarial gain (loss) due to changes in census data | 2.6 | 3.9
Actuarial gain (loss) due to change in trend rate | 1.1 |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | $ (16.5) | $ (20.6)

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