Benefit Plans (Defined Benefit Pension And Other Postretirement Benefits Plans) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 3	$ 8	$ 8
Interest cost	9	10	26	32
Expected return on plan assets	(17)	(17)	(51)	(52)
Amortization of prior service credit	(1)	0	(1)	0
Amortization of actuarial loss	10	9	29	26
Settlement losses	0	0	0	4
Total	3	5	11	18
OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	3	3
Interest cost	1	2	3	5
Expected return on plan assets	(1)	(1)	(3)	(4)
Amortization of prior service credit	0	0	0	0
Amortization of actuarial loss	1	0	3	2
Settlement losses	0	0	0	0
Total	2	2	6	6
IPL [Member] | Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	2	5	5
Interest cost	4	5	12	15
Expected return on plan assets	(8)	(8)	(24)	(24)
Amortization of actuarial loss	5	4	13	11
Total	2	3	6	7
IPL [Member] | OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	1	1	2	2
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of actuarial loss	0	0	1	1
Total	0	0	1	1
WPL [Member] | Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	3	3
Interest cost	3	5	11	14
Expected return on plan assets	(8)	(8)	(23)	(23)
Amortization of actuarial loss	5	4	14	12
Total	1	2	5	6
WPL [Member] | OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	0	1	1
Interest cost	0	1	1	2
Expected return on plan assets	0	(1)	0	(1)
Amortization of actuarial loss	1	1	2	2
Total	$ 2	$ 1	$ 4	$ 4