Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenues:
Electric utility	$ 1,039	$ 939	$ 2,624	$ 2,357
Gas utility	62	50	418	289
Other utility	11	13	35	36
Non-utility	23	22	70	60
Total revenues	1,135	1,024	3,147	2,742
Operating expenses:
Electric production fuel and purchased power	274	207	633	478
Electric transmission service	157	148	428	403
Cost of gas sold	26	18	242	149
Other operation and maintenance	172	171	492	477
Depreciation and amortization	169	165	501	494
Taxes other than income taxes	28	26	82	78
Total operating expenses	826	735	2,378	2,079
Operating income	309	289	769	663
Other (income) and deductions:
Interest expense	83	68	235	206
Equity income from unconsolidated investments, net	(5)	(13)	(37)	(47)
Allowance for funds used during construction	(10)	(7)	(34)	(16)
Other	0	3	0	7
Total other (income) and deductions	68	51	164	150
Income before income taxes	241	238	605	513
Income tax expense (benefit)	14	(21)	26	(66)
Net income	227	259	579	579
Preferred dividend requirements of Interstate Power and Light Company	0	3	0	8
Net income attributable to common shareowners	$ 227	$ 256	$ 579	$ 571
Weighted average number of common shares outstanding:
Basic (in shares)	251,000	250,300	250,800	250,200
Diluted (in shares)	251,300	250,800	251,100	250,600
Earnings per weighted average common share attributable to Alliant Energy common shareowners:
Basic (in dollars per share)	$ 0.90	$ 1.02	$ 2.31	$ 2.28
Diluted (in dollars per share)	$ 0.90	$ 1.02	$ 2.31	$ 2.28
IPL [Member]
Revenues:
Electric utility	$ 596	$ 555	$ 1,438	$ 1,343
Gas utility	33	31	224	165
Other utility	11	13	34	35
Total revenues	640	599	1,696	1,543
Operating expenses:
Electric production fuel and purchased power	140	101	290	215
Electric transmission service	115	103	303	274
Cost of gas sold	14	12	126	84
Other operation and maintenance	90	95	260	253
Depreciation and amortization	95	94	285	281
Taxes other than income taxes	15	14	43	42
Total operating expenses	469	419	1,307	1,149
Operating income	171	180	389	394
Other (income) and deductions:
Interest expense	37	34	111	103
Allowance for funds used during construction	(3)	(2)	(8)	(7)
Other	(1)	0	(2)	2
Total other (income) and deductions	33	32	101	98
Income before income taxes	138	148	288	296
Income tax expense (benefit)	(16)	(12)	(39)	(34)
Net income	154	160	327	330
Preferred dividend requirements of Interstate Power and Light Company	0	3	0	8
Net income attributable to common shareowners	154	157	327	322
WPL [Member]
Revenues:
Electric utility	443	384	1,186	1,014
Gas utility	29	19	194	124
Other utility	0	0	1	1
Total revenues	472	403	1,381	1,139
Operating expenses:
Electric production fuel and purchased power	134	105	343	263
Electric transmission service	42	44	125	128
Cost of gas sold	13	6	117	65
Other operation and maintenance	70	66	193	194
Depreciation and amortization	71	70	211	209
Taxes other than income taxes	11	12	35	35
Total operating expenses	341	303	1,024	894
Operating income	131	100	357	245
Other (income) and deductions:
Interest expense	31	25	86	77
Allowance for funds used during construction	(7)	(5)	(26)	(9)
Other	0	2	0	3
Total other (income) and deductions	24	22	60	71
Income before income taxes	107	78	297	174
Income tax expense (benefit)	16	(15)	50	(41)
Net income	$ 91	$ 93	$ 247	$ 215