Segments Of Business (Schedule Of Segment Of Business) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenues	$ 4,027	$ 4,205	$ 3,669
Depreciation and amortization	676	671	657
Operating income (loss)	943	928	795
Interest expense	394	325	277
Equity income from unconsolidated investments, net	(61)	(51)	(62)
Income tax expense (benefit)	4	22	(74)
Net income attributable to common shareowners	703	686	659
Total assets	21,237	20,163	18,553
Investments in equity method subsidiaries	585	542	508
Construction and acquisition expenditures	1,854	1,484	1,169
IPL [Member]
Segment Reporting Information [Line Items]
Revenues	2,110	2,256	2,063
Operating income (loss)	444	453	460
Interest expense	155	148	139
Income tax expense (benefit)	(58)	(50)	(36)
Net income attributable to common shareowners	366	360	350
Total assets	10,489	10,075
WPL [Member]
Segment Reporting Information [Line Items]
Revenues	1,827	1,856	1,523
Operating income (loss)	472	452	308
Interest expense	149	121	105
Income tax expense (benefit)	60	66	(51)
Total assets	9,634	8,987
Electric [Member]
Segment Reporting Information [Line Items]
Revenues	3,345	3,421	3,081
Depreciation and amortization	602	601	591
Operating income (loss)	827	805	716
Equity income from unconsolidated investments, net	(3)	(1)	(2)
Total assets	17,833	16,571	14,924
Investments in equity method subsidiaries	21	20	17
Construction and acquisition expenditures	1,641	1,318	980
Electric [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	1,761	1,859	1,752
Depreciation and amortization	348	342	338
Operating income (loss)	390	397	420
Total assets	9,311	8,686	8,602
Construction and acquisition expenditures	671	336	342
Electric [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	1,584	1,562	1,329
Depreciation and amortization	254	259	253
Operating income (loss)	437	408	296
Total assets	8,522	7,885	6,322
Construction and acquisition expenditures	970	982	638
Gas [Member]
Segment Reporting Information [Line Items]
Revenues	540	642	456
Depreciation and amortization	60	56	54
Operating income (loss)	70	97	63
Equity income from unconsolidated investments, net	0	0	0
Total assets	1,684	1,631	1,487
Investments in equity method subsidiaries	0	0	0
Construction and acquisition expenditures	90	74	90
Gas [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	300	351	265
Depreciation and amortization	34	32	31
Operating income (loss)	35	53	43
Total assets	921	872	819
Construction and acquisition expenditures	41	36	42
Gas [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	240	291	191
Depreciation and amortization	26	24	23
Operating income (loss)	35	44	20
Total assets	763	759	668
Construction and acquisition expenditures	49	38	48
Other Utility [Member]
Segment Reporting Information [Line Items]
Revenues	52	49	49
Depreciation and amortization	6	7	6
Operating income (loss)	19	3	(11)
Equity income from unconsolidated investments, net	0	0	0
Total assets	606	860	1,103
Investments in equity method subsidiaries	0	0	0
Construction and acquisition expenditures	0	0	0
Other Utility [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	49	46	46
Depreciation and amortization	6	7	6
Operating income (loss)	19	3	(3)
Total assets	257	517	575
Construction and acquisition expenditures	0	0	0
Other Utility [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	3	3	3
Depreciation and amortization	0	0	0
Operating income (loss)	0	0	(8)
Total assets	349	343	528
Construction and acquisition expenditures	0	0	0
ATC Holdings, Non-utility, Parent and Other [Member]
Segment Reporting Information [Line Items]
Revenues	90	93	83
Depreciation and amortization	8	7	6
Operating income (loss)	27	23	27
Interest expense	90	56	33
Equity income from unconsolidated investments, net	(58)	(50)	(60)
Income tax expense (benefit)	2	6	13
Net income attributable to common shareowners	(8)	11	41
Total assets	1,114	1,101	1,039
Investments in equity method subsidiaries	564	522	491
Construction and acquisition expenditures	123	92	99
Utility Business [Member]
Segment Reporting Information [Line Items]
Revenues	3,937	4,112	3,586
Depreciation and amortization	668	664	651
Operating income (loss)	916	905	768
Interest expense	304	269	244
Equity income from unconsolidated investments, net	(3)	(1)	(2)
Income tax expense (benefit)	2	16	(87)
Net income attributable to common shareowners	711	675	618
Total assets	20,123	19,062	17,514
Investments in equity method subsidiaries	21	20	17
Construction and acquisition expenditures	1,731	1,392	1,070
Utility Business [Member] | IPL [Member]
Segment Reporting Information [Line Items]
Revenues	2,110	2,256	2,063
Depreciation and amortization	388	381	375
Operating income (loss)	444	453	460
Interest expense	155	148	139
Income tax expense (benefit)	(58)	(50)	(36)
Net income attributable to common shareowners	366	360	350
Total assets	10,489	10,075	9,996
Construction and acquisition expenditures	712	372	384
Utility Business [Member] | WPL [Member]
Segment Reporting Information [Line Items]
Revenues	1,827	1,856	1,523
Depreciation and amortization	280	283	276
Operating income (loss)	472	452	308
Interest expense	149	121	105
Income tax expense (benefit)	60	66	(51)
Net income attributable to common shareowners	345	315	268
Total assets	9,634	8,987	7,518
Construction and acquisition expenditures	$ 1,019	$ 1,020	$ 686