Segments Of Business (Schedule Of Segment Of Business) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Electric utility	$ 3,372	$ 3,345	$ 3,421
Gas utility	465	540	642
Other	144	142	142
Total revenues	3,981	4,027	4,205
Electric production fuel and purchased power	628	736	830
Electric transmission service	613	583	573
Cost of gas sold	224	299	389
Asset valuation charge for IPL's Lansing Generating Station	60	0	0
Other operation and maintenance	676	675	704
Depreciation and amortization	772	676	671
Interest expense	449	394	325
Equity income from unconsolidated investments, net	(61)	(61)	(51)
Income tax expense (benefit)	(114)	4	22
Other	44	18	56
Net income (loss)	690	703	686
Total assets	22,714	21,237	20,163
Investments in equity method subsidiaries	623	585	542
Construction and acquisition expenditures	2,249	1,854	1,484
IPL [Member]
Segment Reporting Information [Line Items]
Electric utility	1,747	1,761	1,859
Gas utility	250	300	351
Total revenues	2,046	2,110	2,256
Electric production fuel and purchased power	269	282	383
Electric transmission service	417	420	407
Cost of gas sold	123	166	206
Asset valuation charge for IPL's Lansing Generating Station	60	0	0
Depreciation and amortization	404	388	381
Income tax expense (benefit)	(129)	(58)	(50)
Net income (loss)	362	366	360
Total assets	11,407	10,489
WPL [Member]
Segment Reporting Information [Line Items]
Electric utility	1,625	1,584	1,562
Gas utility	215	240	291
Total revenues	1,845	1,827	1,856
Electric production fuel and purchased power	359	455	447
Electric transmission service	196	163	166
Cost of gas sold	101	134	183
Depreciation and amortization	357	280	283
Income tax expense (benefit)	11	60	66
Net income (loss)	345	345	315
Total assets	10,106	9,634
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Electric utility	3,372	3,345	3,421
Gas utility	465	540	642
Other	54	52	49
Total revenues	3,891	3,937	4,112
Electric production fuel and purchased power	628	737	830
Electric transmission service	613	583	573
Cost of gas sold	224	300	389
Asset valuation charge for IPL's Lansing Generating Station	60
Other operation and maintenance	637	624	647
Depreciation and amortization	761	668	664
Interest expense	342	304	269
Equity income from unconsolidated investments, net	(2)	(3)	(1)
Income tax expense (benefit)	(118)	2	16
Other	39	11	50
Net income (loss)	707	711	675
Total assets	21,513	20,123	19,062
Investments in equity method subsidiaries	22	21	20
Construction and acquisition expenditures	2,052	1,731	1,392
IPL [Member]
Segment Reporting Information [Line Items]
Electric utility	1,747	1,761	1,859
Gas utility	250	300	351
Other	49	49	46
Total revenues	2,046	2,110	2,256
Electric production fuel and purchased power	269	282	383
Electric transmission service	417	420	407
Cost of gas sold	123	166	206
Asset valuation charge for IPL's Lansing Generating Station	60
Other operation and maintenance	358	353	369
Depreciation and amortization	404	388	381
Interest expense	177	155	148
Equity income from unconsolidated investments, net	0	0	0
Income tax expense (benefit)	(129)	(58)	(50)
Other	5	38	52
Net income (loss)	362	366	360
Total assets	11,407	10,489	10,075
Investments in equity method subsidiaries	5	5	5
Construction and acquisition expenditures	1,224	712	372
WPL [Member]
Segment Reporting Information [Line Items]
Electric utility	1,625	1,584	1,562
Gas utility	215	240	291
Other	5	3	3
Total revenues	1,845	1,827	1,856
Electric production fuel and purchased power	359	455	447
Electric transmission service	196	163	166
Cost of gas sold	101	134	183
Asset valuation charge for IPL's Lansing Generating Station	0
Other operation and maintenance	279	271	278
Depreciation and amortization	357	280	283
Interest expense	165	149	121
Equity income from unconsolidated investments, net	(2)	(3)	(1)
Income tax expense (benefit)	11	60	66
Other	34	(27)	(2)
Net income (loss)	345	345	315
Total assets	10,106	9,634	8,987
Investments in equity method subsidiaries	17	16	15
Construction and acquisition expenditures	828	1,019	1,020
Other [Member]
Segment Reporting Information [Line Items]
Other	90	90	93
Total revenues	90	90	93
Other operation and maintenance	39	51	57
Depreciation and amortization	11	8	7
Interest expense	107	90	56
Equity income from unconsolidated investments, net	(59)	(58)	(50)
Income tax expense (benefit)	4	2	6
Other	5	5	6
Net income (loss)	(17)	(8)	11
Total assets	1,201	1,114	1,101
Investments in equity method subsidiaries	601	564	522
Construction and acquisition expenditures	$ 197	$ 123	$ 92