Common Equity (Changes in Shareowners' Equity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			$ 6,276
Beginning balance	$ 6,452	$ 6,166	6,276	$ 5,990
Net income attributable to common shareowners	259	227	582	579
Net income			582	579
Common stock dividends	(115)	(106)	(341)	(322)
At-the-market offering program and Shareowner Direct Plan issuances	125	6	201	19
Equity-based compensation plans and other	4	1	4	(1)
Other comprehensive income, net of tax	1		4
Contributions from noncontrolling interest			0	29
Distributions to noncontrolling interest		(29)	0	(29)
Ending balance	6,726		6,726
Ending balance	$ 6,726	$ 6,265	$ 6,726	$ 6,265
Common stock dividends (in dollars per share)	$ 0.4525	$ 0.4275	$ 1.3575	$ 1.2825
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	2,854	2,759	2,777	2,749
At-the-market offering program and Shareowner Direct Plan issuances	125	6	201	19
Equity-based compensation plans and other	3	2	4	(1)
Ending balance	2,982	2,767	2,982	2,767
Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,606	3,387	3,509	3,250
Net income attributable to common shareowners	259	227	582	579
Common stock dividends	(115)	(106)	(341)	(322)
Equity-based compensation plans and other				1
Ending balance	3,750	3,508	3,750	3,508
Accumulated Other Comprehensive Income (Loss) [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3	0	0	0
Other comprehensive income, net of tax	1		4
Ending balance	4	0	4	0
Shares in Deferred Compensation Trust [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	(14)	(12)	(13)	(12)
Equity-based compensation plans and other	1	(1)		(1)
Ending balance	(13)	(13)	(13)	(13)
Noncontrolling Interest [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	29	0	0
Contributions from noncontrolling interest				29
Distributions to noncontrolling interest		(29)		(29)
Ending balance	0	0	0	0
IPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,808
Beginning balance	3,869	3,782	3,808	3,769
Net income	170	154	331	327
Common stock dividends	(70)	(80)	(210)	(240)
Capital contributions from parent	20		60	0
Ending balance	3,989		3,989
Ending balance	3,989	3,856	3,989	3,856
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	2,847	2,807	2,807	2,807
Capital contributions from parent	20		60
Ending balance	2,867	2,807	2,867	2,807
IPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	989	942	968	929
Net income	170	154	331	327
Common stock dividends	(70)	(80)	(210)	(240)
Ending balance	1,089	1,016	1,089	1,016
WPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,491
Beginning balance	3,739	3,183	3,491	2,823
Net income	107	91	267	247
Common stock dividends	(46)	(44)	(138)	(133)
Equity-based compensation plans and other				(1)
Capital contributions from parent	65	155	245	420
Contributions from noncontrolling interest			0	29
Distributions to noncontrolling interest		(29)	0	(29)
Ending balance	3,865		3,865
Ending balance	3,865	3,356	3,865	3,356
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	2,413	1,968	2,233	1,704
Equity-based compensation plans and other				(1)
Capital contributions from parent	65	155	245	420
Ending balance	2,478	2,123	2,478	2,123
WPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,260	1,120	1,192	1,053
Net income	107	91	267	247
Common stock dividends	(46)	(44)	(138)	(133)
Ending balance	1,321	1,167	1,321	1,167
WPL [Member] | Noncontrolling Interest [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	29	0	0
Contributions from noncontrolling interest				29
Distributions to noncontrolling interest		(29)		(29)
Ending balance	$ 0	$ 0	$ 0	$ 0