Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues:
Electric utility	$ 999	$ 995	$ 2,579	$ 2,562
Gas utility	49	47	322	400
Other utility	12	13	36	38
Non-utility	21	22	68	66
Total revenues	1,081	1,077	3,005	3,066
Operating expenses:
Electric production fuel and purchased power	192	231	493	553
Electric transmission service	165	154	464	438
Cost of gas sold	13	12	152	226
Asset valuation charge for IPL's Lansing Generating Station	0	0	60	0
Other operation and maintenance	174	160	510	499
Depreciation and amortization	195	170	571	503
Taxes other than income taxes	29	28	90	87
Total operating expenses	768	755	2,340	2,306
Operating income	313	322	665	760
Other (income) and deductions:
Interest expense	114	99	329	289
Equity income from unconsolidated investments, net	(14)	(14)	(44)	(45)
Allowance for funds used during construction	(20)	(28)	(58)	(71)
Other	0	1	2	2
Total other (income) and deductions	80	58	229	175
Income before income taxes	233	264	436	585
Income tax expense (benefit)	(62)	5	(104)	3
Net income attributable to common shareowners	$ 295	$ 259	$ 540	$ 582
Weighted average number of common shares outstanding:
Basic (in shares)	256,600	253,500	256,400	252,100
Diluted (in shares)	256,900	253,800	256,700	252,400
Earnings per weighted average common share attributable to Alliant Energy common shareowners:
Basic (in dollars per share)	$ 1.15	$ 1.02	$ 2.11	$ 2.31
Diluted (in dollars per share)	$ 1.15	$ 1.02	$ 2.10	$ 2.31
IPL [Member]
Revenues:
Electric utility	$ 523	$ 551	$ 1,318	$ 1,370
Gas utility	27	31	175	224
Other utility	11	12	34	36
Total revenues	561	594	1,527	1,630
Operating expenses:
Electric production fuel and purchased power	79	99	195	213
Electric transmission service	115	115	317	316
Cost of gas sold	8	12	85	127
Asset valuation charge for IPL's Lansing Generating Station	0	0	60	0
Other operation and maintenance	96	84	281	264
Depreciation and amortization	100	97	294	288
Taxes other than income taxes	14	14	45	43
Total operating expenses	412	421	1,277	1,251
Operating income	149	173	250	379
Other (income) and deductions:
Interest expense	44	38	128	113
Allowance for funds used during construction	(13)	(6)	(34)	(13)
Other	(4)	2	(4)	3
Total other (income) and deductions	27	34	90	103
Income before income taxes	122	139	160	276
Income tax expense (benefit)	(68)	(31)	(112)	(55)
Net income attributable to common shareowners	190	170	272	331
WPL [Member]
Revenues:
Electric utility	476	444	1,261	1,192
Gas utility	22	16	147	176
Other utility	1	1	2	2
Total revenues	499	461	1,410	1,370
Operating expenses:
Electric production fuel and purchased power	112	132	298	341
Electric transmission service	49	39	148	122
Cost of gas sold	5	0	67	99
Other operation and maintenance	72	64	200	197
Depreciation and amortization	91	71	269	208
Taxes other than income taxes	14	13	41	40
Total operating expenses	343	319	1,023	1,007
Operating income	156	142	387	363
Other (income) and deductions:
Interest expense	42	38	124	110
Allowance for funds used during construction	(7)	(22)	(24)	(58)
Other	3	(2)	4	(3)
Total other (income) and deductions	38	14	104	49
Income before income taxes	118	128	283	314
Income tax expense (benefit)	4	21	13	47
Net income attributable to common shareowners	$ 114	$ 107	$ 270	$ 267