Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 67	$ 39
Accounts receivable, less allowance for expected credit losses	481	440
Production fuel, at weighted average cost	39	51
Gas stored underground, at weighted average cost	27	82
Materials and supplies, at weighted average cost	119	113
Regulatory assets	88	104
Other	271	240
Total current assets	1,092	1,069
Property, plant and equipment, net	15,192	14,987
Investments:
ATC Holdings	346	338
Other	187	179
Total investments	533	517
Other assets:
Regulatory assets	1,831	1,836
Deferred charges and other	191	144
Total other assets	2,022	1,980
Total assets	18,839	18,553
Current liabilities:
Current maturities of long-term debt	333	633
Commercial paper	276	515
Accounts payable	383	436
Accrued taxes	66	58
Regulatory liabilities	251	186
Other	212	226
Total current liabilities	1,521	2,054
Long-term debt, net (excluding current portion)	7,383	6,735
Other liabilities:
Deferred tax liabilities	1,958	1,927
Regulatory liabilities	1,121	1,085
Pension and other benefit obligations	363	374
Other	416	388
Total other liabilities	3,858	3,774
Commitments and contingencies (Note 12)
Common equity:
Common stock	3	3
Additional paid-in capital	2,750	2,749
Retained earnings	3,336	3,250
Shares in deferred compensation trust - 381,397 and 383,532 shares at a weighted average cost of $31.17 and $30.59 per share	(12)	(12)
Total common equity	6,077	5,990
Total liabilities and equity	18,839	18,553
IPL [Member]
Current assets:
Cash and cash equivalents	62	34
Accounts receivable, less allowance for expected credit losses	257	241
Income tax refunds receivable	25	8
Production fuel, at weighted average cost	28	29
Gas stored underground, at weighted average cost	11	40
Materials and supplies, at weighted average cost	71	70
Regulatory assets	60	73
Other	85	69
Total current assets	599	564
Property, plant and equipment, net	7,976	7,983
Other assets:
Regulatory assets	1,372	1,370
Deferred charges and other	103	79
Total other assets	1,475	1,449
Total assets	10,050	9,996
Current liabilities:
Accounts payable	135	173
Accounts payable to associated companies	46	39
Accrued taxes	57	56
Accrued interest	35	36
Regulatory liabilities	122	84
Other	62	67
Total current liabilities	457	455
Long-term debt, net (excluding current portion)	3,644	3,643
Other liabilities:
Deferred tax liabilities	1,107	1,083
Regulatory liabilities	632	607
Pension and other benefit obligations	124	127
Other	311	312
Total other liabilities	2,174	2,129
Commitments and contingencies (Note 12)
Common equity:
Common stock	33	33
Additional paid-in capital	2,807	2,807
Retained earnings	935	929
Total common equity	3,775	3,769
Total liabilities and equity	10,050	9,996
WPL [Member]
Current assets:
Cash and cash equivalents	4	2
Accounts receivable, less allowance for expected credit losses	211	188
Production fuel, at weighted average cost	11	23
Gas stored underground, at weighted average cost	16	42
Materials and supplies, at weighted average cost	45	41
Regulatory assets	28	31
Prepaid gross receipts tax	30	40
Other	102	86
Total current assets	447	453
Property, plant and equipment, net	6,747	6,538
Other assets:
Regulatory assets	459	466
Deferred charges and other	90	61
Total other assets	549	527
Total assets	7,743	7,518
Current liabilities:
Current maturities of long-term debt	250	250
Commercial paper	157	236
Accounts payable	185	190
Accounts payable to associated companies	34	39
Regulatory liabilities	129	102
Other	102	73
Total current liabilities	857	890
Long-term debt, net (excluding current portion)	2,180	2,179
Other liabilities:
Deferred tax liabilities	759	753
Regulatory liabilities	489	478
Pension and other benefit obligations	154	159
Other	253	236
Total other liabilities	1,655	1,626
Commitments and contingencies (Note 12)
Common equity:
Common stock	66	66
Additional paid-in capital	1,884	1,704
Retained earnings	1,101	1,053
Total common equity	3,051	2,823
Total liabilities and equity	$ 7,743	$ 7,518