Condensed Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenues:
Electric utility	$ 773	$ 701
Gas utility	262	170
Other utility	11	13
Non-utility	22	17
Total revenues	1,068	901
Operating expenses:
Electric production fuel and purchased power	168	133
Electric transmission service	138	134
Cost of gas sold	168	100
Other operation and maintenance	153	146
Depreciation and amortization	166	164
Taxes other than income taxes	27	26
Total operating expenses	820	703
Operating income	248	198
Other (income) and deductions:
Interest expense	74	69
Equity income from unconsolidated investments, net	(15)	(15)
Allowance for funds used during construction	(11)	(4)
Other	0	2
Total other (income) and deductions	48	52
Income before income taxes	200	146
Income tax expense (benefit)	8	(28)
Net income	192	174
Preferred dividend requirements of Interstate Power and Light Company	0	3
Net income attributable to common shareowners	$ 192	$ 171
Weighted average number of common shares outstanding:
Basic (in shares)	250,600	250,000
Diluted (in shares)	250,900	250,400
Earnings per weighted average common share attributable to Alliant Energy common shareowners (basic) (in dollars per share)	$ 0.77	$ 0.68
Earnings per weighted average common share attributable to Alliant Energy common shareowners (diluted) (in dollars per share)	$ 0.77	$ 0.68
IPL [Member]
Revenues:
Electric utility	$ 400	$ 386
Gas utility	139	91
Other utility	11	12
Total revenues	550	489
Operating expenses:
Electric production fuel and purchased power	67	59
Electric transmission service	97	92
Cost of gas sold	85	50
Other operation and maintenance	83	77
Depreciation and amortization	94	94
Taxes other than income taxes	14	14
Total operating expenses	440	386
Operating income	110	103
Other (income) and deductions:
Interest expense	37	35
Allowance for funds used during construction	(3)	(2)
Total other (income) and deductions	34	33
Income before income taxes	76	70
Income tax expense (benefit)	(11)	(12)
Net income	87	82
Preferred dividend requirements of Interstate Power and Light Company	0	3
Net income attributable to common shareowners	87	79
WPL [Member]
Revenues:
Electric utility	373	315
Gas utility	123	79
Other utility	0	1
Total revenues	496	395
Operating expenses:
Electric production fuel and purchased power	101	74
Electric transmission service	41	42
Cost of gas sold	83	50
Other operation and maintenance	58	59
Depreciation and amortization	70	69
Taxes other than income taxes	12	11
Total operating expenses	365	305
Operating income	131	90
Other (income) and deductions:
Interest expense	27	26
Allowance for funds used during construction	(9)	(2)
Other	0	1
Total other (income) and deductions	18	25
Income before income taxes	113	65
Income tax expense (benefit)	21	(19)
Net income	$ 92	$ 84