Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 62	$ 20
Accounts receivable, less allowance for expected credit losses	475	516
Production fuel, at weighted average cost	62	53
Gas stored underground, at weighted average cost	79	132
Materials and supplies, at weighted average cost	202	140
Regulatory assets	232	166
Other	160	223
Total current assets	1,272	1,250
Property, plant and equipment, net	17,157	16,247
Investments:
ATC Holdings	386	358
Other	216	201
Total investments	602	559
Other assets:
Regulatory assets	2,029	1,880
Deferred charges and other	177	227
Total other assets	2,206	2,107
Total assets	21,237	20,163
Current liabilities:
Current maturities of long-term debt	809	408
Commercial paper	475	642
Accounts payable	611	756
Regulatory liabilities	107	206
Other	302	351
Total current liabilities	2,304	2,363
Long-term debt, net (excluding current portion)	8,225	7,668
Other liabilities:
Deferred tax liabilities	2,042	1,943
Regulatory liabilities	1,023	1,118
Pension and other benefit obligations	249	277
Other	617	518
Total other liabilities	3,931	3,856
Commitments and contingencies (Note 17)
Common equity:
Common stock	3	3
Additional paid-in capital	3,030	2,777
Retained earnings	3,756	3,509
Accumulated other comprehensive income	1	0
Shares in deferred compensation trust - 379,006 and 402,134 shares at a weighted average cost of $34.48 and $32.63 per share	(13)	(13)
Total common equity	6,777	6,276
Total liabilities and equity	21,237	20,163
IPL [Member]
Current assets:
Cash and cash equivalents	53	15
Accounts receivable, less allowance for expected credit losses	242	259
Production fuel, at weighted average cost	27	23
Gas stored underground, at weighted average cost	35	60
Materials and supplies, at weighted average cost	122	83
Regulatory assets	93	85
Other	51	93
Total current assets	623	618
Property, plant and equipment, net	8,298	8,046
Other assets:
Regulatory assets	1,484	1,301
Deferred charges and other	84	110
Total other assets	1,568	1,411
Total assets	10,489	10,075
Current liabilities:
Current maturities of long-term debt	500	0
Commercial paper	0	0
Accounts payable	262	239
Accrued taxes	50	52
Accrued interest	40	35
Regulatory liabilities	72	114
Other	101	141
Total current liabilities	1,025	581
Long-term debt, net (excluding current portion)	3,445	3,646
Other liabilities:
Deferred tax liabilities	1,091	1,047
Regulatory liabilities	572	640
Pension and other benefit obligations	51	62
Other	331	291
Total other liabilities	2,045	2,040
Commitments and contingencies (Note 17)
Common equity:
Common stock	33	33
Additional paid-in capital	2,887	2,807
Retained earnings	1,054	968
Total common equity	3,974	3,808
Total liabilities and equity	10,489	10,075
WPL [Member]
Current assets:
Cash and cash equivalents	7	5
Accounts receivable, less allowance for expected credit losses	219	244
Production fuel, at weighted average cost	35	29
Gas stored underground, at weighted average cost	44	73
Materials and supplies, at weighted average cost	77	54
Regulatory assets	139	81
Prepaid gross receipts tax	49	42
Other	43	60
Total current assets	613	588
Property, plant and equipment, net	8,415	7,722
Other assets:
Regulatory assets	545	579
Deferred charges and other	61	98
Total other assets	606	677
Total assets	9,634	8,987
Current liabilities:
Current maturities of long-term debt	0	0
Commercial paper	318	290
Accounts payable	293	456
Accrued interest	40	38
Regulatory liabilities	35	92
Other	89	73
Total current liabilities	775	949
Long-term debt, net (excluding current portion)	3,070	2,770
Other liabilities:
Deferred tax liabilities	827	789
Regulatory liabilities	451	478
Pension and other benefit obligations	121	140
Other	493	370
Total other liabilities	1,892	1,777
Commitments and contingencies (Note 17)
Common equity:
Common stock	66	66
Additional paid-in capital	2,478	2,233
Retained earnings	1,353	1,192
Total common equity	3,897	3,491
Total liabilities and equity	$ 9,634	$ 8,987