Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Revenues:
Electric utility	$ 768	$ 773
Gas utility	276	262
Other utility	11	11
Non-utility	22	22
Total revenues	1,077	1,068
Operating expenses:
Electric production fuel and purchased power	157	168
Electric transmission service	146	138
Cost of gas sold	181	168
Other operation and maintenance	174	153
Depreciation and amortization	166	166
Taxes other than income taxes	31	27
Total operating expenses	855	820
Operating income	222	248
Other (income) and deductions:
Interest expense	94	74
Equity income from unconsolidated investments, net	(17)	(15)
Allowance for funds used during construction	(19)	(11)
Other	3	0
Total other (income) and deductions	61	48
Income before income taxes	161	200
Income tax expense (benefit)	(2)	8
Net income	163	192
Net income attributable to common shareowners	$ 163	$ 192
Weighted average number of common shares outstanding:
Basic (in shares)	251,200	250,600
Diluted (in shares)	251,400	250,900
Earnings per weighted average common share attributable to Alliant Energy common shareowners:
Basic (in dollars per share)	$ 0.65	$ 0.77
Diluted (in dollars per share)	$ 0.65	$ 0.77
IPL [Member]
Revenues:
Electric utility	$ 388	$ 400
Gas utility	150	139
Other utility	11	11
Total revenues	549	550
Operating expenses:
Electric production fuel and purchased power	47	67
Electric transmission service	104	97
Cost of gas sold	95	85
Other operation and maintenance	95	83
Depreciation and amortization	96	94
Taxes other than income taxes	16	14
Total operating expenses	453	440
Operating income	96	110
Other (income) and deductions:
Interest expense	37	37
Allowance for funds used during construction	(3)	(3)
Other	1	0
Total other (income) and deductions	35	34
Income before income taxes	61	76
Income tax expense (benefit)	(11)	(11)
Net income	72	87
WPL [Member]
Revenues:
Electric utility	380	373
Gas utility	126	123
Total revenues	506	496
Operating expenses:
Electric production fuel and purchased power	109	101
Electric transmission service	42	41
Cost of gas sold	86	83
Other operation and maintenance	66	58
Depreciation and amortization	68	70
Taxes other than income taxes	14	12
Total operating expenses	385	365
Operating income	121	131
Other (income) and deductions:
Interest expense	36	27
Allowance for funds used during construction	(16)	(9)
Other	1	0
Total other (income) and deductions	21	18
Income before income taxes	100	113
Income tax expense (benefit)	12	21
Net income	$ 88	$ 92