Segments Of Business (Schedule Of Segments Of Business) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 943	$ 817	$ 2,012	$ 1,718
Operating income (loss)	212	176	460	374
Net income attributable to common shareowners	159	144	351	315
Net income	159	146	351	320
IPL [Member]
Segment Reporting Information [Line Items]
Revenues	506	455	1,056	944
Operating income (loss)	109	111	218	214
Net income attributable to common shareowners	87	86	173	165
Net income	87	88	173	170
WPL [Member]
Segment Reporting Information [Line Items]
Revenues	413	341	909	736
Operating income (loss)	95	55	227	145
Net income	63	38	156	122
Electric [Member]
Segment Reporting Information [Line Items]
Revenues	812	717	1,586	1,418
Operating income (loss)	195	164	376	311
Electric [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	442	402	843	788
Operating income (loss)	104	107	179	179
Electric [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	370	315	743	630
Operating income (loss)	91	57	197	132
Gas [Member]
Segment Reporting Information [Line Items]
Revenues	94	69	356	239
Operating income (loss)	8	3	65	47
Gas [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	52	43	191	134
Operating income (loss)	4	3	36	33
Gas [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	42	26	165	105
Operating income (loss)	4	0	29	14
Other Utility [Member]
Segment Reporting Information [Line Items]
Revenues	13	10	23	23
Operating income (loss)	1	(1)	4	1
Other Utility [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	12	10	22	22
Operating income (loss)	1	1	3	2
Other Utility [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	1	0	1	1
Operating income (loss)	0	(2)	1	(1)
Utility Business [Member]
Segment Reporting Information [Line Items]
Revenues	919	796	1,965	1,680
Operating income (loss)	204	166	445	359
Net income attributable to common shareowners	150	124	329	287
ATC Holdings, Non-Utility, Parent and Other [Member]
Segment Reporting Information [Line Items]
Revenues	24	21	47	38
Operating income (loss)	8	10	15	15
Net income attributable to common shareowners	$ 9	$ 20	$ 22	$ 28