Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 206	$ 20
Accounts receivable, less allowance for expected credit losses	486	516
Production fuel, at weighted average cost	44	53
Gas stored underground, at weighted average cost	87	132
Materials and supplies, at weighted average cost	196	140
Regulatory assets	179	166
Other	174	223
Total current assets	1,372	1,250
Property, plant and equipment, net	16,633	16,247
Investments:
ATC Holdings	380	358
Other	214	201
Total investments	594	559
Other assets:
Regulatory assets	2,090	1,880
Deferred charges and other	215	227
Total other assets	2,305	2,107
Total assets	20,904	20,163
Current liabilities:
Current maturities of long-term debt	409	408
Commercial paper	451	642
Other short-term borrowings	50	0
Accounts payable	604	756
Regulatory liabilities	92	206
Other	329	351
Total current liabilities	1,935	2,363
Long-term debt, net (excluding current portion)	8,429	7,668
Other liabilities:
Deferred tax liabilities	1,913	1,943
Regulatory liabilities	1,095	1,118
Pension and other benefit obligations	262	277
Other	544	518
Total other liabilities	3,814	3,856
Commitments and contingencies (Note 13)
Common equity:
Common stock	3	3
Additional paid-in capital	2,982	2,777
Retained earnings	3,750	3,509
Accumulated other comprehensive income	4	0
Shares in deferred compensation trust - 393,781 and 402,134 shares at a weighted average cost of $34.13 and $32.63 per share	(13)	(13)
Total common equity	6,726	6,276
Total liabilities and equity	20,904	20,163
IPL [Member]
Current assets:
Cash and cash equivalents	188	15
Accounts receivable, less allowance for expected credit losses	258	259
Production fuel, at weighted average cost	22	23
Gas stored underground, at weighted average cost	40	60
Materials and supplies, at weighted average cost	111	83
Regulatory assets	86	85
Other	70	93
Total current assets	775	618
Property, plant and equipment, net	8,042	8,046
Other assets:
Regulatory assets	1,504	1,301
Deferred charges and other	106	110
Total other assets	1,610	1,411
Total assets	10,427	10,075
Current liabilities:
Accounts payable	255	239
Accounts payable to associated companies	59	28
Accrued taxes	68	52
Accrued interest	41	35
Regulatory liabilities	63	114
Other	84	113
Total current liabilities	570	581
Long-term debt, net (excluding current portion)	3,944	3,646
Other liabilities:
Deferred tax liabilities	987	1,047
Regulatory liabilities	592	640
Pension and other benefit obligations	59	62
Other	286	291
Total other liabilities	1,924	2,040
Commitments and contingencies (Note 13)
Common equity:
Common stock	33	33
Additional paid-in capital	2,867	2,807
Retained earnings	1,089	968
Total common equity	3,989	3,808
Total liabilities and equity	10,427	10,075
WPL [Member]
Current assets:
Cash and cash equivalents	16	5
Accounts receivable, less allowance for expected credit losses	214	244
Production fuel, at weighted average cost	21	29
Gas stored underground, at weighted average cost	47	73
Materials and supplies, at weighted average cost	82	54
Regulatory assets	93	81
Prepaid gross receipts tax	36	42
Other	50	60
Total current assets	559	588
Property, plant and equipment, net	8,085	7,722
Other assets:
Regulatory assets	586	579
Deferred charges and other	71	98
Total other assets	657	677
Total assets	9,301	8,987
Current liabilities:
Commercial paper	120	290
Accounts payable	281	456
Regulatory liabilities	29	92
Other	117	111
Total current liabilities	547	949
Long-term debt, net (excluding current portion)	3,069	2,770
Other liabilities:
Deferred tax liabilities	796	789
Regulatory liabilities	503	478
Pension and other benefit obligations	128	140
Other	393	370
Total other liabilities	1,820	1,777
Commitments and contingencies (Note 13)
Common equity:
Common stock	66	66
Additional paid-in capital	2,478	2,233
Retained earnings	1,321	1,192
Total common equity	3,865	3,491
Total liabilities and equity	$ 9,301	$ 8,987