Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenues:
Electric utility	$ 799	$ 812	$ 1,567	$ 1,586
Gas utility	77	94	353	356
Other utility	13	13	25	23
Non-utility	23	24	45	47
Total revenues	912	943	1,990	2,012
Operating expenses:
Electric production fuel and purchased power	166	191	322	359
Electric transmission service	138	133	284	271
Cost of gas sold	33	48	215	216
Other operation and maintenance	163	166	338	320
Depreciation and amortization	167	166	333	332
Taxes other than income taxes	28	27	59	54
Total operating expenses	695	731	1,551	1,552
Operating income	217	212	439	460
Other (income) and deductions:
Interest expense	96	78	190	152
Equity income from unconsolidated investments, net	(14)	(16)	(31)	(32)
Allowance for funds used during construction	(24)	(13)	(43)	(24)
Other	(1)	0	2	1
Total other (income) and deductions	57	49	118	97
Income before income taxes	160	163	321	363
Income tax expense (benefit)	0	4	(2)	12
Net income			323	351
Net income attributable to common shareowners	$ 160	$ 159	$ 323	$ 351
Weighted average number of common shares outstanding:
Basic (in shares)	251,700	250,900	251,400	250,700
Diluted (in shares)	251,900	251,100	251,600	251,000
Earnings per weighted average common share attributable to Alliant Energy common shareowners:
Basic (in dollars per share)	$ 0.64	$ 0.63	$ 1.28	$ 1.40
Diluted (in dollars per share)	$ 0.64	$ 0.63	$ 1.28	$ 1.40
IPL [Member]
Revenues:
Electric utility	$ 431	$ 442	$ 819	$ 843
Gas utility	44	52	194	191
Other utility	12	12	24	22
Total revenues	487	506	1,037	1,056
Operating expenses:
Electric production fuel and purchased power	66	83	113	150
Electric transmission service	96	91	201	188
Cost of gas sold	20	27	116	112
Other operation and maintenance	85	87	181	171
Depreciation and amortization	96	95	191	189
Taxes other than income taxes	14	14	29	28
Total operating expenses	377	397	831	838
Operating income	110	109	206	218
Other (income) and deductions:
Interest expense	37	37	74	74
Allowance for funds used during construction	(4)	(3)	(8)	(5)
Other	1	0	3	(1)
Total other (income) and deductions	34	34	69	68
Income before income taxes	76	75	137	150
Income tax expense (benefit)	(13)	(12)	(24)	(23)
Net income	89	87	161	173
WPL [Member]
Revenues:
Electric utility	368	370	748	743
Gas utility	33	42	159	165
Other utility	1	1	1	1
Total revenues	402	413	908	909
Operating expenses:
Electric production fuel and purchased power	99	108	209	209
Electric transmission service	42	41	83	83
Cost of gas sold	13	21	99	104
Other operation and maintenance	67	67	133	123
Depreciation and amortization	69	69	137	139
Taxes other than income taxes	13	12	27	24
Total operating expenses	303	318	688	682
Operating income	99	95	220	227
Other (income) and deductions:
Interest expense	36	28	72	55
Allowance for funds used during construction	(19)	(10)	(35)	(18)
Other	(4)	0	(3)	0
Total other (income) and deductions	13	18	34	37
Income before income taxes	86	77	186	190
Income tax expense (benefit)	14	14	26	34
Net income	$ 72	$ 63	$ 160	$ 156