Benefit Plans (Defined Benefit Pension And Other Postretirement Benefits Plans) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 2	$ 8	$ 7
Interest cost	10	13	32	37
Expected return on plan assets	(17)	(15)	(52)	(45)
Amortization of actuarial loss	9	9	26	27
Settlement losses	0	0	4	0
Total	5	9	18	26
OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	3	3
Interest cost	2	2	5	6
Expected return on plan assets	(1)	(1)	(4)	(4)
Amortization of actuarial loss	0	1	2	2
Settlement losses	0	0	0	0
Total	2	3	6	7
IPL [Member] | Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	1	5	4
Interest cost	5	6	15	17
Expected return on plan assets	(8)	(7)	(24)	(21)
Amortization of actuarial loss	4	4	11	12
Total	3	4	7	12
IPL [Member] | OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	1	1	2	3
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of actuarial loss	0	1	1	1
Total	0	1	1	2
WPL [Member] | Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	3	3
Interest cost	5	5	14	16
Expected return on plan assets	(8)	(6)	(23)	(20)
Amortization of actuarial loss	4	4	12	13
Total	2	4	6	12
WPL [Member] | OPEB Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	1	1	2	3
Expected return on plan assets	(1)	0	(1)	(1)
Amortization of actuarial loss	1	0	2	1
Total	$ 1	$ 1	$ 4	$ 4