Common Equity (Changes in Shareowners' Equity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			$ 6,777
Beginning balance	$ 6,791	$ 6,452	6,777	$ 6,276
Net income attributable to common shareowners	295	259	540	582
Net income			540	582
Common stock dividends	(123)	(115)	(369)	(341)
At-the-market offering program and Shareowner Direct Plan issuances	6	125	18	201
Equity-based compensation plans and other	3	4	4	4
Other comprehensive income (loss), net of tax	(4)	1	(2)	4
Ending balance	6,968		6,968
Ending balance	$ 6,968	$ 6,726	$ 6,968	$ 6,726
Common stock dividends (in dollars per share)	$ 0.48	$ 0.4525	$ 1.44	$ 1.3575
Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	$ 3	$ 3	$ 3	$ 3
Ending balance	3	3	3	3
Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,042	2,854	3,030	2,777
At-the-market offering program and Shareowner Direct Plan issuances	6	125	18	201
Equity-based compensation plans and other	4	3	4	4
Ending balance	3,052	2,982	3,052	2,982
Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,755	3,606	3,756	3,509
Net income attributable to common shareowners	295	259	540	582
Common stock dividends	(123)	(115)	(369)	(341)
Ending balance	3,927	3,750	3,927	3,750
Accumulated Other Comprehensive Income (Loss) [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3	3	1	0
Other comprehensive income (loss), net of tax	(4)	1	(2)	4
Ending balance	(1)	4	(1)	4
Shares in Deferred Compensation Trust [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	(12)	(14)	(13)	(13)
Equity-based compensation plans and other	(1)	1
Ending balance	(13)	(13)	(13)	(13)
IPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,974
Beginning balance	4,080	3,869	3,974	3,808
Net income attributable to common shareowners	190	170	272	331
Net income	190	170	272	331
Common stock dividends	(50)	(70)	(151)	(210)
Capital contributions from parent	200	20	325	60
Ending balance	4,420		4,420
Ending balance	4,420	3,989	4,420	3,989
IPL [Member] | Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	33	33	33	33
Ending balance	33	33	33	33
IPL [Member] | Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,012	2,847	2,887	2,807
Capital contributions from parent	200	20	325	60
Ending balance	3,212	2,867	3,212	2,867
IPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,035	989	1,054	968
Net income	190	170	272	331
Common stock dividends	(50)	(70)	(151)	(210)
Ending balance	1,175	1,089	1,175	1,089
WPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,897
Beginning balance	4,010	3,739	3,897	3,491
Net income attributable to common shareowners	114	107	270	267
Net income	114	107	270	267
Common stock dividends	(49)	(46)	(147)	(138)
Capital contributions from parent		65	55	245
Ending balance	4,075		4,075
Ending balance	4,075	3,865	4,075	3,865
WPL [Member] | Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	66	66	66	66
Ending balance	66	66	66	66
WPL [Member] | Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,533	2,413	2,478	2,233
Capital contributions from parent		65	55	245
Ending balance	2,533	2,478	2,533	2,478
WPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,411	1,260	1,353	1,192
Net income	114	107	270	267
Common stock dividends	(49)	(46)	(147)	(138)
Ending balance	$ 1,476	$ 1,321	$ 1,476	$ 1,321