Benefit Plans (Funded Status of Benefits Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligations	$ 875	$ 1,251
Change in benefit obligation:
Net benefit obligation at January 1	1,251	1,351
Service cost	9	11	$ 11
Interest cost	36	34	43
Plan participants' contributions	0	0
Actuarial (gain) loss	(269)	(46)
Gross benefits paid	(152)	(99)
Net benefit obligation at December 31	875	1,251	1,351
Change in plan assets:
Fair value of plan assets at January 1	1,011	984
Actual return on plan assets	(204)	87
Employer contributions	51	39
Plan participants' contributions	0	0
Gross benefits paid	(152)	(99)
Fair value of plan assets at December 31	706	1,011	984
Under funded status at December 31	(169)	(240)
Fair value of plan assets	706	1,011
Pension Plans, Defined Benefit [Member] | IPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligations	389	567
Change in benefit obligation:
Net benefit obligation at January 1	567	615
Service cost	6	7	7
Interest cost	16	16	20
Plan participants' contributions	0	0
Actuarial (gain) loss	(123)	(23)
Gross benefits paid	(77)	(48)
Net benefit obligation at December 31	389	567	615
Change in plan assets:
Fair value of plan assets at January 1	462	453
Actual return on plan assets	(92)	40
Employer contributions	51	17
Plan participants' contributions	0	0
Gross benefits paid	(77)	(48)
Fair value of plan assets at December 31	344	462	453
Under funded status at December 31	(45)	(105)
Fair value of plan assets	344	462
Pension Plans, Defined Benefit [Member] | WPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligations	381	546
Change in benefit obligation:
Net benefit obligation at January 1	546	588
Service cost	3	4	4
Interest cost	16	15	19
Plan participants' contributions	0	0
Actuarial (gain) loss	(117)	(18)
Gross benefits paid	(67)	(43)
Net benefit obligation at December 31	381	546	588
Change in plan assets:
Fair value of plan assets at January 1	450	436
Actual return on plan assets	(92)	39
Employer contributions	0	18
Plan participants' contributions	0	0
Gross benefits paid	(67)	(43)
Fair value of plan assets at December 31	291	450	436
Under funded status at December 31	(90)	(96)
Fair value of plan assets	291	450
Other Postretirement Benefits Plans [Member]
Change in benefit obligation:
Net benefit obligation at January 1	210	227
Service cost	3	4	3
Interest cost	6	5	7
Plan participants' contributions	4	5
Actuarial (gain) loss	(37)	(12)
Gross benefits paid	(18)	(19)
Net benefit obligation at December 31	168	210	227
Change in plan assets:
Fair value of plan assets at January 1	106	108
Actual return on plan assets	(17)	4
Employer contributions	8	8
Plan participants' contributions	4	5
Gross benefits paid	(18)	(19)
Fair value of plan assets at December 31	83	106	108
Under funded status at December 31	(85)	(104)
Other Postretirement Benefits Plans [Member] | IPL [Member]
Change in benefit obligation:
Net benefit obligation at January 1	84	91
Service cost	1	1	1
Interest cost	2	2	3
Plan participants' contributions	2	2
Actuarial (gain) loss	(14)	(4)
Gross benefits paid	(7)	(8)
Net benefit obligation at December 31	68	84	91
Change in plan assets:
Fair value of plan assets at January 1	74	74
Actual return on plan assets	(12)	4
Employer contributions	1	2
Plan participants' contributions	2	2
Gross benefits paid	(7)	(8)
Fair value of plan assets at December 31	58	74	74
Under funded status at December 31	(10)	(10)
Other Postretirement Benefits Plans [Member] | WPL [Member]
Change in benefit obligation:
Net benefit obligation at January 1	81	89
Service cost	1	1	2
Interest cost	2	2	3
Plan participants' contributions	2	2
Actuarial (gain) loss	(13)	(5)
Gross benefits paid	(8)	(8)
Net benefit obligation at December 31	65	81	89
Change in plan assets:
Fair value of plan assets at January 1	17	18
Actual return on plan assets	(2)	0
Employer contributions	5	5
Plan participants' contributions	2	2
Gross benefits paid	(8)	(8)
Fair value of plan assets at December 31	14	17	$ 18
Under funded status at December 31	$ (51)	$ (64)