Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenues:
Electric utility	$ 789	$ 799	$ 1,580	$ 1,567
Gas utility	69	77	273	353
Other utility	10	13	24	25
Non-utility	26	23	48	45
Total revenues	894	912	1,925	1,990
Operating expenses:
Electric production fuel and purchased power	138	166	301	322
Electric transmission service	147	138	300	284
Cost of gas sold	25	33	139	215
Asset valuation charge for IPL's Lansing Generating Station	60	0	60	0
Other operation and maintenance	177	163	336	338
Depreciation and amortization	188	167	376	333
Taxes other than income taxes	29	28	61	59
Total operating expenses	764	695	1,573	1,551
Operating income	130	217	352	439
Other (income) and deductions:
Interest expense	108	96	215	190
Equity income from unconsolidated investments, net	(15)	(14)	(31)	(31)
Allowance for funds used during construction	(19)	(24)	(38)	(43)
Other	2	(1)	4	2
Total other (income) and deductions	76	57	150	118
Income (loss) before income taxes	54	160	202	321
Income tax expense (benefit)	(33)	0	(43)	(2)
Net income attributable to common shareowners	$ 87	$ 160	$ 245	$ 323
Weighted average number of common shares outstanding:
Basic (in shares)	256,400	251,700	256,300	251,400
Diluted (in shares)	256,700	251,900	256,600	251,600
Earnings per weighted average common share attributable to Alliant Energy common shareowners:
Basic (in dollars per share)	$ 0.34	$ 0.64	$ 0.96	$ 1.28
Diluted (in dollars per share)	$ 0.34	$ 0.64	$ 0.95	$ 1.28
IPL [Member]
Revenues:
Electric utility	$ 404	$ 431	$ 795	$ 819
Gas utility	40	44	148	194
Other utility	9	12	23	24
Total revenues	453	487	966	1,037
Operating expenses:
Electric production fuel and purchased power	48	66	116	113
Electric transmission service	99	96	202	201
Cost of gas sold	17	20	77	116
Asset valuation charge for IPL's Lansing Generating Station	60	0	60	0
Other operation and maintenance	102	85	187	181
Depreciation and amortization	97	96	193	191
Taxes other than income taxes	14	14	30	29
Total operating expenses	437	377	865	831
Operating income	16	110	101	206
Other (income) and deductions:
Interest expense	42	37	84	74
Allowance for funds used during construction	(11)	(4)	(21)	(8)
Other	0	1	0	3
Total other (income) and deductions	31	34	63	69
Income (loss) before income taxes	(15)	76	38	137
Income tax expense (benefit)	(33)	(13)	(43)	(24)
Net income attributable to common shareowners	18	89	81	161
WPL [Member]
Revenues:
Electric utility	385	368	785	748
Gas utility	29	33	125	159
Other utility	1	1	1	1
Total revenues	415	402	911	908
Operating expenses:
Electric production fuel and purchased power	90	99	186	209
Electric transmission service	49	42	98	83
Cost of gas sold	8	13	62	99
Other operation and maintenance	67	67	128	133
Depreciation and amortization	87	69	178	137
Taxes other than income taxes	14	13	28	27
Total operating expenses	315	303	680	688
Operating income	100	99	231	220
Other (income) and deductions:
Interest expense	41	36	82	72
Allowance for funds used during construction	(8)	(19)	(17)	(35)
Other	0	(4)	2	(3)
Total other (income) and deductions	33	13	67	34
Income (loss) before income taxes	67	86	164	186
Income tax expense (benefit)	3	14	8	26
Net income attributable to common shareowners	$ 64	$ 72	$ 156	$ 160