Segments Of Business (Schedule Of Segments Of Business) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 1,135	$ 1,024	$ 3,147	$ 2,742
Operating income (loss)	309	289	769	663
Net income (loss) attributable to common shareowners	227	256	579	571
Net income	227	259	579	579
IPL [Member]
Segment Reporting Information [Line Items]
Revenues	640	599	1,696	1,543
Operating income (loss)	171	180	389	394
Net income (loss) attributable to common shareowners	154	157	327	322
Net income	154	160	327	330
WPL [Member]
Segment Reporting Information [Line Items]
Revenues	472	403	1,381	1,139
Operating income (loss)	131	100	357	245
Net income	91	93	247	215
Electric [Member]
Segment Reporting Information [Line Items]
Revenues	1,039	939	2,624	2,357
Operating income (loss)	304	290	680	601
Electric [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	596	555	1,438	1,343
Operating income (loss)	174	186	353	365
Electric [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	443	384	1,186	1,014
Operating income (loss)	130	104	327	236
Gas [Member]
Segment Reporting Information [Line Items]
Revenues	62	50	418	289
Operating income (loss)	(3)	(5)	62	42
Gas [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	33	31	224	165
Operating income (loss)	(3)	(3)	33	30
Gas [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	29	19	194	124
Operating income (loss)	0	(2)	29	12
Other Utility [Member]
Segment Reporting Information [Line Items]
Revenues	11	13	35	36
Operating income (loss)	1	(5)	4	(4)
Other Utility [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	11	13	34	35
Operating income (loss)	0	(3)	3	(1)
Other Utility [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	1	1
Operating income (loss)	1	(2)	1	(3)
Utility Business [Member]
Segment Reporting Information [Line Items]
Revenues	1,112	1,002	3,077	2,682
Operating income (loss)	302	280	746	639
Net income (loss) attributable to common shareowners	245	250	574	537
ATC Holdings, Non-Utility, Parent and Other [Member]
Segment Reporting Information [Line Items]
Revenues	23	22	70	60
Operating income (loss)	7	9	23	24
Net income (loss) attributable to common shareowners	$ (18)	$ 6	$ 5	$ 34