Segments Of Business (Tables)

12 Months Ended

Dec. 31, 2023

Segment Reporting Information [Line Items]

Schedule of Segments of Business

Certain financial information relating to Alliant Energy’s business segments, which represent the services provided to its customers, was as follows (in millions):

					ATC Holdings,
	Utility				Non-utility,	Alliant Energy
2023	Electric	Gas	Other	Total	Parent and Other	Consolidated
Revenues	$3,345	$540	$52	$3,937	$90	$4,027
Depreciation and amortization	602	60	6	668	8	676
Operating income	827	70	19	916	27	943
Interest expense				304	90	394
Equity income from unconsolidated investments, net	(3)	—	—	(3)	(58)	(61)
Income taxes				2	2	4
Net income (loss) attributable to Alliant Energy common shareowners				711	(8)	703
Total assets	17,833	1,684	606	20,123	1,114	21,237
Investments in equity method subsidiaries	21	—	—	21	564	585
Construction and acquisition expenditures	1,641	90	—	1,731	123	1,854

					ATC Holdings,
	Utility				Non-utility,	Alliant Energy
2022	Electric	Gas	Other	Total	Parent and Other	Consolidated
Revenues	$3,421	$642	$49	$4,112	$93	$4,205
Depreciation and amortization	601	56	7	664	7	671
Operating income	805	97	3	905	23	928
Interest expense				269	56	325
Equity income from unconsolidated investments, net	(1)	—	—	(1)	(50)	(51)
Income taxes				16	6	22
Net income attributable to Alliant Energy common shareowners				675	11	686
Total assets	16,571	1,631	860	19,062	1,101	20,163
Investments in equity method subsidiaries	20	—	—	20	522	542
Construction and acquisition expenditures	1,318	74	—	1,392	92	1,484

					ATC Holdings,
	Utility				Non-utility,	Alliant Energy
2021	Electric	Gas	Other	Total	Parent and Other	Consolidated
Revenues	$3,081	$456	$49	$3,586	$83	$3,669
Depreciation and amortization	591	54	6	651	6	657
Operating income (loss)	716	63	(11)	768	27	795
Interest expense				244	33	277
Equity income from unconsolidated investments, net	(2)	—	—	(2)	(60)	(62)
Income tax expense (benefit)				(87)	13	(74)
Net income attributable to Alliant Energy common shareowners				618	41	659
Total assets	14,924	1,487	1,103	17,514	1,039	18,553
Investments in equity method subsidiaries	17	—	—	17	491	508
Construction and acquisition expenditures	980	90	—	1,070	99	1,169

IPL [Member]

Segment Reporting Information [Line Items]

Schedule of Segments of Business

Certain financial information relating to IPL’s business segments, which represent the services provided to its customers, was as follows (in millions):

2023	Electric	Gas	Other	Total
Revenues	$1,761	$300	$49	$2,110
Depreciation and amortization	348	34	6	388
Operating income	390	35	19	444
Interest expense				155
Income tax benefit				(58)
Net income available for common stock				366
Total assets	9,311	921	257	10,489
Construction and acquisition expenditures	671	41	—	712

2022	Electric	Gas	Other	Total
Revenues	$1,859	$351	$46	$2,256
Depreciation and amortization	342	32	7	381
Operating income	397	53	3	453
Interest expense				148
Income tax benefit				(50)
Net income available for common stock				360
Total assets	8,686	872	517	10,075
Construction and acquisition expenditures	336	36	—	372

2021	Electric	Gas	Other	Total
Revenues	$1,752	$265	$46	$2,063
Depreciation and amortization	338	31	6	375
Operating income (loss)	420	43	(3)	460
Interest expense				139
Income tax benefit				(36)
Net income available for common stock				350
Total assets	8,602	819	575	9,996
Construction and acquisition expenditures	342	42	—	384

WPL [Member]

Segment Reporting Information [Line Items]

Schedule of Segments of Business

Certain financial information relating to WPL’s business segments, which represent the services provided to its customers, was as follows (in millions):

2023	Electric	Gas	Other	Total
Revenues	$1,584	$240	$3	$1,827
Depreciation and amortization	254	26	—	280
Operating income	437	35	—	472
Interest expense				149
Income taxes				60
Net income				345
Total assets	8,522	763	349	9,634
Construction and acquisition expenditures	970	49	—	1,019

2022	Electric	Gas	Other	Total
Revenues	$1,562	$291	$3	$1,856
Depreciation and amortization	259	24	—	283
Operating income	408	44	—	452
Interest expense				121
Income taxes				66
Net income				315
Total assets	7,885	759	343	8,987
Construction and acquisition expenditures	982	38	—	1,020

2021	Electric	Gas	Other	Total
Revenues	$1,329	$191	$3	$1,523
Depreciation and amortization	253	23	—	276
Operating income (loss)	296	20	(8)	308
Interest expense				105
Income tax benefit				(51)
Net income				268
Total assets	6,322	668	528	7,518
Construction and acquisition expenditures	638	48	—	686