Consolidated Statements Of Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues:
Electric utility	$ 3,421	$ 3,081	$ 2,920
Gas utility	642	456	373
Other utility	49	49	49
Non-utility	93	83	74
Total revenues	4,205	3,669	3,416
Operating expenses:
Electric production fuel and purchased power	830	642	652
Electric transmission service	573	537	449
Cost of gas sold	389	258	182
Other operation and maintenance	704	676	670
Depreciation and amortization	671	657	615
Taxes other than income taxes	110	104	108
Total operating expenses	3,277	2,874	2,676
Operating income (loss)	928	795	740
Other (income) and deductions:
Interest expense	325	277	275
Equity income from unconsolidated investments, net	(51)	(62)	(61)
Allowance for funds used during construction	(60)	(25)	(55)
Other	6	5	14
Total other (income) and deductions	220	195	173
Income before income taxes	708	600	567
Income tax expense (benefit)	22	(74)	(57)
Net income	686	674	624
Preferred dividend requirements of Interstate Power and Light Company	0	15	10
Net income attributable to common shareowners	$ 686	$ 659	$ 614
Weighted average number of common shares outstanding:
Basic (in shares)	250.9	250.2	248.4
Diluted (in shares)	251.2	250.7	248.7
Earnings per weighted average common share attributable to Alliant Energy common shareowners:
Basic (in dollars per share)	$ 2.73	$ 2.63	$ 2.47
Diluted (in dollars per share)	$ 2.73	$ 2.63	$ 2.47
IPL [Member]
Revenues:
Electric utility	$ 1,859	$ 1,752	$ 1,695
Gas utility	351	265	208
Other utility	46	46	44
Total revenues	2,256	2,063	1,947
Operating expenses:
Electric production fuel and purchased power	383	295	352
Electric transmission service	407	367	298
Cost of gas sold	206	149	99
Other operation and maintenance	369	362	375
Depreciation and amortization	381	375	356
Taxes other than income taxes	57	55	57
Total operating expenses	1,803	1,603	1,537
Operating income (loss)	453	460	410
Other (income) and deductions:
Interest expense	148	139	139
Allowance for funds used during construction	(11)	(9)	(24)
Other	6	1	8
Total other (income) and deductions	143	131	123
Income before income taxes	310	329	287
Income tax expense (benefit)	(50)	(36)	(47)
Net income	360	365	334
Preferred dividend requirements of Interstate Power and Light Company	0	15	10
Net income attributable to common shareowners	360	350	324
WPL [Member]
Revenues:
Electric utility	1,562	1,329	1,225
Gas utility	291	191	165
Other utility	3	3	5
Total revenues	1,856	1,523	1,395
Operating expenses:
Electric production fuel and purchased power	447	347	300
Electric transmission service	166	170	151
Cost of gas sold	183	109	83
Other operation and maintenance	278	268	254
Depreciation and amortization	283	276	254
Taxes other than income taxes	47	45	47
Total operating expenses	1,404	1,215	1,089
Operating income (loss)	452	308	306
Other (income) and deductions:
Interest expense	121	105	104
Allowance for funds used during construction	(49)	(16)	(31)
Other	(1)	2	3
Total other (income) and deductions	71	91	76
Income before income taxes	381	217	230
Income tax expense (benefit)	66	(51)	(19)
Net income	$ 315	$ 268	$ 249