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