Common Equity (Changes in Shareowners' Equity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			$ 6,276
Beginning balance	$ 6,328	$ 6,077	6,276	$ 5,990
Net income attributable to common shareowners	160	159	323	351
Net income			323	351
Common stock dividends	(113)	(108)	(226)	(215)
At-the-market offering program and Shareowner Direct Plan issuances	70	6	76	13
Equity-based compensation plans and other	3	3	0	(2)
Other comprehensive income, net of tax	4		3
Contributions from noncontrolling interest		29	0	29
Ending balance	6,452		6,452
Ending balance	$ 6,452	$ 6,166	$ 6,452	$ 6,166
Common stock dividends (in dollars per share)	$ 0.4525	$ 0.4275	$ 0.905	$ 0.855
Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	$ 3	$ 3	$ 3	$ 3
At-the-market offering program and Shareowner Direct Plan issuances
Ending balance	3	3	3	3
Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,780	2,750	2,777	2,749
At-the-market offering program and Shareowner Direct Plan issuances	70	6	76	13
Equity-based compensation plans and other	4	3	1	(3)
Ending balance	2,854	2,759	2,854	2,759
Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,559	3,336	3,509	3,250
Net income attributable to common shareowners	160	159	323	351
Common stock dividends	(113)	(108)	(226)	(215)
Equity-based compensation plans and other				1
Ending balance	3,606	3,387	3,606	3,387
Accumulated Other Comprehensive Income (Loss) [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	(1)	0	0	0
Other comprehensive income, net of tax	4		3
Ending balance	3	0	3	0
Shares in Deferred Compensation Trust [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	(13)	(12)	(13)	(12)
Equity-based compensation plans and other	(1)		(1)
Ending balance	(14)	(12)	(14)	(12)
Noncontrolling Interest [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	0	0	0
Contributions from noncontrolling interest		29		29
Ending balance	0	29	0	29
IPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,808
Beginning balance	3,810	3,775	3,808	3,769
Net income	89	87	161	173
Common stock dividends	(70)	(80)	(140)	(160)
Capital contributions from parent	40		40	0
Ending balance	3,869		3,869
Ending balance	3,869	3,782	3,869	3,782
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	2,807	2,807	2,807	2,807
Capital contributions from parent	40		40
Ending balance	2,847	2,807	2,847	2,807
IPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	970	935	968	929
Net income	89	87	161	173
Common stock dividends	(70)	(80)	(140)	(160)
Ending balance	989	942	989	942
WPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,491
Beginning balance	3,713	3,051	3,491	2,823
Net income	72	63	160	156
Common stock dividends	(46)	(44)	(92)	(89)
Equity-based compensation plans and other		(1)		(1)
Capital contributions from parent		85	180	265
Contributions from noncontrolling interest		29	0	29
Ending balance	3,739		3,739
Ending balance	3,739	3,183	3,739	3,183
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	1,884	2,233	1,704
Equity-based compensation plans and other		(1)		(1)
Capital contributions from parent		85	180	265
Ending balance	2,413	1,968	2,413	1,968
WPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,234	1,101	1,192	1,053
Net income	72	63	160	156
Common stock dividends	(46)	(44)	(92)	(89)
Ending balance	1,260	1,120	1,260	1,120
WPL [Member] | Noncontrolling Interest [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	0	0	0
Contributions from noncontrolling interest		29		29
Ending balance	$ 0	$ 29	$ 0	$ 29