Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Pension settlement losses	$ (3)	$ (6)	$ (5)
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	9	11
Interest cost	47	36	34
Expected return on plan assets	(53)	(69)	(69)
Amortization of prior service cost (credit)	(1)	(1)	0
Amortization of actuarial loss	28	32	39
Settlement losses	0	26	0
Total	26	33	15
Pension settlement losses	7
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	3	4
Interest cost	9	6	5
Expected return on plan assets	(5)	(5)	(5)
Amortization of prior service cost (credit)	0	0	0
Amortization of actuarial loss	1	2	5
Settlement losses	0	0	0
Total	7	6	9
IPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension settlement losses	(2)	(6)	(1)
IPL [Member] | Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	6	7
Interest cost	21	16	16
Expected return on plan assets	(26)	(31)	(32)
Amortization of actuarial loss	11	13	17
Settlement losses	0	13	0
Total	9	17	8
Pension settlement losses	7
IPL [Member] | Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	1
Interest cost	3	2	2
Expected return on plan assets	(3)	(4)	(3)
Amortization of actuarial loss	1	1	2
Settlement losses	0	0	0
Total	2	0	2
WPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension settlement losses	3	1	(2)
WPL [Member] | Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	3	4
Interest cost	20	16	15
Expected return on plan assets	(22)	(31)	(31)
Amortization of actuarial loss	13	15	19
Settlement losses	0	13	0
Total	13	16	7
WPL [Member] | Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	1
Interest cost	3	2	2
Expected return on plan assets	(1)	(1)	0
Amortization of actuarial loss	1	2	2
Settlement losses	0	0	0
Total	$ 4	$ 4	$ 5