Common Equity (Changes in Shareowners' Equity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			$ 6,777
Beginning balance	$ 6,817	$ 6,328	6,777	$ 6,276
Net income attributable to common shareowners	87	160	245	323
Net income			245	323
Common stock dividends	(123)	(113)	(246)	(226)
Shareowner Direct Plan issuances	6	70	12	76
Equity-based compensation plans and other	3	3	1	0
Other comprehensive income (loss), net of tax	1	4	2	3
Ending balance	6,791		6,791
Ending balance	$ 6,791	$ 6,452	$ 6,791	$ 6,452
Common stock dividends (in dollars per share)	$ 0.48	$ 0.4525	$ 0.96	$ 0.905
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	3,033	2,780	3,030	2,777
Shareowner Direct Plan issuances	6	70	12	76
Equity-based compensation plans and other	3	4		1
Ending balance	3,042	2,854	3,042	2,854
Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,791	3,559	3,756	3,509
Net income attributable to common shareowners	87	160	245	323
Common stock dividends	(123)	(113)	(246)	(226)
Ending balance	3,755	3,606	3,755	3,606
Accumulated Other Comprehensive Income (Loss) [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2	(1)	1	0
Other comprehensive income (loss), net of tax	1	4	2	3
Ending balance	3	3	3	3
Shares in Deferred Compensation Trust [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	(12)	(13)	(13)	(13)
Equity-based compensation plans and other		(1)	1	(1)
Ending balance	(12)	(14)	(12)	(14)
IPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,974
Beginning balance	4,037	3,810	3,974	3,808
Net income attributable to common shareowners	18	89	81	161
Net income	18	89	81	161
Common stock dividends	(50)	(70)	(100)	(140)
Capital contributions from parent	75	40	125	40
Ending balance	4,080		4,080
Ending balance	4,080	3,869	4,080	3,869
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	2,937	2,807	2,887	2,807
Capital contributions from parent	75	40	125	40
Ending balance	3,012	2,847	3,012	2,847
IPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,067	970	1,054	968
Net income	18	89	81	161
Common stock dividends	(50)	(70)	(100)	(140)
Ending balance	1,035	989	1,035	989
WPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,897
Beginning balance	3,995	3,713	3,897	3,491
Net income attributable to common shareowners	64	72	156	160
Net income	64	72	156	160
Common stock dividends	(49)	(46)	(98)	(92)
Capital contributions from parent			55	180
Ending balance	4,010		4,010
Ending balance	4,010	3,739	4,010	3,739
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			55	180
Ending balance	2,533	2,413	2,533	2,413
WPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,396	1,234	1,353	1,192
Net income	64	72	156	160
Common stock dividends	(49)	(46)	(98)	(92)
Ending balance	$ 1,411	$ 1,260	$ 1,411	$ 1,260