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Retirement Plans and Postretirement Benefit Plans - Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Pension Plans [Member] |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation, Beginning | $ 358.5 | $ 502.9 |
Service cost | 5.4 | 7.6 |
Interest cost | 15.9 | 15.7 |
Plan settlements | (62.8) | (95.8) |
Actuarial losses (gains) | 0.8 | (56.9) |
Benefits paid | (14.1) | (15.0) |
Benefit Obligation, Ending | 303.7 | 358.5 | $ 502.9
Pension Plans [Member] | Og and E [Member] |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation, Beginning | 288.5 | 363.2 |
Service cost | 4.4 | 6.2 |
Interest cost | 12.6 | 12.1 |
Plan settlements | (57.7) | (38.8) |
Actuarial losses (gains) | 2.7 | (41.3) |
Benefits paid | (11.9) | (12.9) |
Benefit Obligation, Ending | 238.6 | 288.5 | 363.2
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] |  |  |
Fair Value of Plan Assets, Beginning | 238.9 | 353.0 |
Actual return on plans' assets | 22.1 | (62.4) |
Employer contributions | 0.0 | 0.0 |
Plan settlements | (57.7) | (38.8) |
Benefits paid | (11.9) | (12.9) |
Fair Value of Plan Assets, Ending | 191.4 | 238.9 | 353.0
Funded status at end of year | (47.2) | (49.6) |
Accumulated Benefit Obligation | 226.5 | 275.2 |
Pension Plans, Defined Benefit [Member] |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Service cost | 5.4 | 7.6 | 11.2
Interest cost | 15.9 | 15.7 | 13.3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] |  |  |
Fair Value of Plan Assets, Beginning | 293.0 | 486.0 |
Actual return on plans' assets | 27.6 | (82.2) |
Employer contributions | 0.0 | 0.0 |
Plan settlements | (62.8) | (95.8) |
Benefits paid | (14.1) | (15.0) |
Fair Value of Plan Assets, Ending | 243.7 | 293.0 | 486.0
Funded status at end of year | (60.0) | (65.5) |
Accumulated Benefit Obligation | 289.5 | 342.7 |
Pension Plans, Defined Benefit [Member] | Og and E [Member] |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Service cost | 4.4 | 6.2 | 7.7
Interest cost | 12.6 | 12.1 | 9.7
Restoration of Retirement Income Plan [Member] |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation, Beginning | 5.8 | 5.9 |
Service cost | 1.0 | 1.1 | 0.8
Interest cost | 0.3 | 0.2 | 0.1
Plan settlements | (1.4) | (1.5) |
Actuarial losses (gains) | (0.2) | 0.1 |
Benefits paid | 0.0 | 0.0 |
Benefit Obligation, Ending | 5.5 | 5.8 | 5.9
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] |  |  |
Fair Value of Plan Assets, Beginning | 0.0 | 0.0 |
Actual return on plans' assets | 0.0 | 0.0 |
Employer contributions | 1.4 | 0.2 |
Plan settlements | (1.4) | (0.2) |
Benefits paid | 0.0 | 0.0 |
Fair Value of Plan Assets, Ending | 0.0 | 0.0 | 0.0
Funded status at end of year | (5.5) | (5.8) |
Accumulated Benefit Obligation | 4.9 | 4.8 |
Restoration of Retirement Income Plan [Member] | Og and E [Member] |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation, Beginning | 0.5 | 0.5 |
Service cost | 0.0 | 0.0 | 0.0
Interest cost | 0.0 | 0.0 | 0.0
Plan settlements | (0.7) | 0.0 |
Actuarial losses (gains) | 0.2 | 0.0 |
Benefits paid | 0.0 | 0.0 |
Benefit Obligation, Ending | 0.0 | 0.5 | 0.5
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] |  |  |
Fair Value of Plan Assets, Beginning | 0.0 | 0.0 |
Actual return on plans' assets | 0.0 | 0.0 |
Employer contributions | 0.7 | 0.0 |
Plan settlements | (0.7) | 0.0 |
Benefits paid | 0.0 | 0.0 |
Fair Value of Plan Assets, Ending | 0.0 | 0.0 | 0.0
Funded status at end of year | 0.0 | (0.5) |
Accumulated Benefit Obligation | 0.0 | 0.4 |
Other Postretirement Benefits Plan [Member] |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation, Beginning | 101.9 | 137.3 |
Service cost | 0.1 | 0.2 | 0.2
Interest cost | 5.2 | 3.5 | 3.4
Participants' contributions | 3.4 | 3.5 |
Actuarial losses (gains) | 4.9 | (29.1) |
Benefits paid | (12.2) | (13.5) |
Benefit Obligation, Ending | 103.3 | 101.9 | 137.3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] |  |  |
Fair Value of Plan Assets, Beginning | 32.8 | 44.3 |
Actual return on plans' assets | 1.9 | (8.2) |
Employer contributions | 6.8 | 6.7 |
Participants' contributions | 3.4 | 3.5 |
Benefits paid | (12.2) | (13.5) |
Fair Value of Plan Assets, Ending | 32.7 | 32.8 | 44.3
Accumulated Benefit Obligation | 70.6 | 69.1 |
Other Postretirement Benefits Plan [Member] | Og and E [Member] |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation, Beginning | 76.4 | 102.4 |
Service cost | 0.1 | 0.1 | 0.1
Interest cost | 3.9 | 2.7 | 2.6
Participants' contributions | 2.4 | 2.4 |
Actuarial losses (gains) | 4.0 | (21.0) |
Benefits paid | (9.5) | (10.2) |
Benefit Obligation, Ending | 77.3 | 76.4 | 102.4
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] |  |  |
Fair Value of Plan Assets, Beginning | 29.8 | 39.9 |
Actual return on plans' assets | (1.7) | (7.4) |
Employer contributions | 5.2 | 5.1 |
Participants' contributions | 2.4 | 2.4 |
Benefits paid | (9.5) | (10.2) |
Fair Value of Plan Assets, Ending | 29.6 | 29.8 | $ 39.9
Accumulated Benefit Obligation | $ 47.7 | $ 46.6 |

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- Definition Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 60 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480266/715-60-50-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a)(6) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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