Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 157	$ 20
Accounts receivable, less allowance for expected credit losses	428	516
Production fuel, at weighted average cost	60	53
Gas stored underground, at weighted average cost	64	132
Materials and supplies, at weighted average cost	158	140
Regulatory assets	193	166
Other	132	223
Total current assets	1,192	1,250
Property, plant and equipment, net	16,396	16,247
Investments:
ATC Holdings	363	358
Other	206	201
Total investments	569	559
Other assets:
Regulatory assets	1,887	1,880
Deferred charges and other	196	227
Total other assets	2,083	2,107
Total assets	20,240	20,163
Current liabilities:
Current maturities of long-term debt	808	408
Commercial paper	60	642
Other short-term borrowings	50	0
Accounts payable	518	756
Regulatory liabilities	129	206
Other	343	351
Total current liabilities	1,908	2,363
Long-term debt, net (excluding current portion)	8,132	7,668
Other liabilities:
Deferred tax liabilities	1,957	1,943
Regulatory liabilities	1,102	1,118
Pension and other benefit obligations	273	277
Other	540	518
Total other liabilities	3,872	3,856
Commitments and contingencies (Note 13)
Common equity:
Common stock	3	3
Additional paid-in capital	2,780	2,777
Retained earnings	3,559	3,509
Accumulated other comprehensive loss	(1)	0
Shares in deferred compensation trust - 394,363 and 402,134 shares at a weighted average cost of $33.12 and $32.63 per share	(13)	(13)
Total common equity	6,328	6,276
Total liabilities and equity	20,240	20,163
IPL [Member]
Current assets:
Cash and cash equivalents	35	15
Accounts receivable, less allowance for expected credit losses	191	259
Production fuel, at weighted average cost	26	23
Gas stored underground, at weighted average cost	26	60
Materials and supplies, at weighted average cost	92	83
Regulatory assets	75	85
Other	49	93
Total current assets	494	618
Property, plant and equipment, net	8,112	8,046
Other assets:
Regulatory assets	1,308	1,301
Deferred charges and other	93	110
Total other assets	1,401	1,411
Total assets	10,007	10,075
Current liabilities:
Accounts payable	222	239
Accounts payable to associated companies	37	28
Accrued taxes	59	52
Accrued interest	35	35
Regulatory liabilities	73	114
Other	92	113
Total current liabilities	518	581
Long-term debt, net (excluding current portion)	3,647	3,646
Other liabilities:
Deferred tax liabilities	1,053	1,047
Regulatory liabilities	624	640
Pension and other benefit obligations	61	62
Other	294	291
Total other liabilities	2,032	2,040
Commitments and contingencies (Note 13)
Common equity:
Common stock	33	33
Additional paid-in capital	2,807	2,807
Retained earnings	970	968
Total common equity	3,810	3,808
Total liabilities and equity	10,007	10,075
WPL [Member]
Current assets:
Cash and cash equivalents	86	5
Accounts receivable, less allowance for expected credit losses	225	244
Production fuel, at weighted average cost	34	29
Gas stored underground, at weighted average cost	38	73
Materials and supplies, at weighted average cost	63	54
Regulatory assets	118	81
Prepaid gross receipts tax	31	42
Other	26	60
Total current assets	621	588
Property, plant and equipment, net	7,792	7,722
Other assets:
Regulatory assets	579	579
Deferred charges and other	82	98
Total other assets	661	677
Total assets	9,074	8,987
Current liabilities:
Commercial paper	60	290
Accounts payable	233	456
Regulatory liabilities	56	92
Other	163	111
Total current liabilities	512	949
Long-term debt, net (excluding current portion)	3,067	2,770
Other liabilities:
Deferred tax liabilities	787	789
Regulatory liabilities	478	478
Pension and other benefit obligations	139	140
Other	378	370
Total other liabilities	1,782	1,777
Commitments and contingencies (Note 13)
Common equity:
Common stock	66	66
Additional paid-in capital	2,413	2,233
Retained earnings	1,234	1,192
Total common equity	3,713	3,491
Total liabilities and equity	$ 9,074	$ 8,987