Benefit Plans (Defined Benefit Pension And Other Postretirement Benefits Plans) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 2	$ 6	$ 5
Interest cost	9	11	17	22
Expected return on plan assets	(17)	(17)	(34)	(35)
Amortization of actuarial loss	9	8	19	17
Settlement losses	0	0	0	4
Total	4	4	8	13
OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	2	2
Interest cost	1	1	2	3
Expected return on plan assets	(1)	(1)	(2)	(3)
Amortization of actuarial loss	1	1	2	2
Settlement losses	0	0	0	0
Total	2	2	4	4
IPL [Member] | Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	4	3
Interest cost	4	5	8	10
Expected return on plan assets	(8)	(8)	(16)	(16)
Amortization of actuarial loss	4	3	8	7
Total	2	2	4	4
IPL [Member] | OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	1	1
Interest cost	0	0	1	1
Expected return on plan assets	(1)	(1)	(2)	(2)
Amortization of actuarial loss	1	1	1	1
Total	1	1	1	1
WPL [Member] | Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	2	2
Interest cost	4	4	8	9
Expected return on plan assets	(7)	(7)	(15)	(15)
Amortization of actuarial loss	4	4	9	8
Total	2	2	4	4
WPL [Member] | OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	0	1
Interest cost	1	0	1	1
Expected return on plan assets	0	0	0	0
Amortization of actuarial loss	0	1	1	1
Total	$ 1	$ 2	$ 2	$ 3