Common Equity (Changes in Shareowners' Equity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			$ 5,990
Beginning balance	$ 6,077	$ 5,966	5,990	$ 5,888
Net income attributable to common shareowners	159	144	351	315
Net income	159	146	351	320
Common stock dividends	(108)	(101)	(215)	(203)
Shareowner Direct Plan issuances	6	7	13	15
Equity-based compensation plans and other	3	3	(2)	4
Contributions from noncontrolling interest	29		29
Ending balance	6,137		6,137
Ending balance	$ 6,166	$ 6,019	$ 6,166	$ 6,019
Common stock dividends (in dollars per share)	$ 0.4275	$ 0.4025	$ 0.855	$ 0.805
Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	$ 3	$ 3	$ 3	$ 2
Shareowner Direct Plan issuances				1
Ending balance	3	3	3	3
Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,750	2,712	2,749	2,704
Shareowner Direct Plan issuances	6	7	13	14
Equity-based compensation plans and other	3	3	(3)	4
Ending balance	2,759	2,722	2,759	2,722
Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,336	3,063	3,250	2,994
Net income attributable to common shareowners	159	144	351	315
Common stock dividends	(108)	(101)	(215)	(203)
Equity-based compensation plans and other			1
Ending balance	3,387	3,106	3,387	3,106
Accumulated Other Comprehensive Loss [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	(1)	0	(1)
Ending balance	0	(1)	0	(1)
Shares in Deferred Compensation Trust [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	(12)	(11)	(12)	(11)
Ending balance	(12)	(11)	(12)	(11)
Noncontrolling Interest [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0		0
Contributions from noncontrolling interest	29		29
Ending balance	29		29
Cumulative Preferred Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance		200		200
Ending balance		200		200
IPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			3,769
Beginning balance	3,775	3,942	3,769	3,964
Net income attributable to common shareowners	87	86	173	165
Net income	87	88	173	170
Common stock dividends	(80)	(99)	(160)	(200)
Capital contributions from parent		50	0	50
Ending balance	3,782		3,782
Ending balance	3,782	3,979	3,782	3,979
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	2,752	2,807	2,752
Capital contributions from parent		50		50
Ending balance	2,807	2,802	2,807	2,802
IPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	935	957	929	979
Net income attributable to common shareowners	87	86	173	165
Common stock dividends	(80)	(99)	(160)	(200)
Ending balance	942	944	942	944
IPL [Member] | Cumulative Preferred Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	200	0	200
Ending balance	0	200	0	200
WPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance			2,823
Beginning balance	3,051	2,645	2,823	2,478
Net income	63	38	156	122
Common stock dividends	(44)	(43)	(89)	(85)
Equity-based compensation plans and other	(1)		(1)
Capital contributions from parent	85	85	265	210
Contributions from noncontrolling interest	29		29
Ending balance	3,154		3,154
Ending balance	3,183	2,725	3,183	2,725
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	1,884	1,584	1,704	1,459
Equity-based compensation plans and other	(1)		(1)
Capital contributions from parent	85	85	265	210
Ending balance	1,968	1,669	1,968	1,669
WPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,101	995	1,053	953
Net income	63	38	156	122
Common stock dividends	(44)	(43)	(89)	(85)
Ending balance	1,120	990	1,120	990
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	$ 29	$ 0	$ 29	$ 0