Common Equity (Changes in Shareowners' Equity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	$ 5,990
Beginning balance	5,990	$ 5,888
Net income attributable to common shareowners	192	171
Net income	192	174
Common stock dividends	(107)	(102)
Shareowner Direct Plan issuances	7	8
Equity-based compensation plans and other	(5)	1
Ending balance	6,077
Ending balance	$ 6,077	$ 5,966
Common stock dividends (in dollars per share)	$ 0.4275	$ 0.4025
Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	$ 3	$ 2
Shareowner Direct Plan issuances		1
Ending balance	3	3
Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,749	2,704
Shareowner Direct Plan issuances	7	7
Equity-based compensation plans and other	(6)	1
Ending balance	2,750	2,712
Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,250	2,994
Net income attributable to common shareowners	192	171
Common stock dividends	(107)	(102)
Equity-based compensation plans and other	1
Ending balance	3,336	3,063
Accumulated Other Comprehensive Income (Loss) [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	(1)
Ending balance	0	(1)
Shares in Deferred Compensation Trust [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	(12)	(11)
Ending balance	(12)	(11)
Cumulative Preferred Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	200
Ending balance	0	200
IPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	3,769
Beginning balance	3,769	3,964
Net income attributable to common shareowners	87	79
Net income	87	82
Common stock dividends	(81)	(101)
Ending balance	3,775
Ending balance	3,775	3,942
IPL [Member] | Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	33	33
Ending balance	33	33
IPL [Member] | Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,807	2,752
Ending balance	2,807	2,752
IPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	929	979
Net income attributable to common shareowners	87	79
Common stock dividends	(81)	(101)
Ending balance	935	957
IPL [Member] | Cumulative Preferred Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	0	200
Ending balance	0	200
WPL [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	2,823
Beginning balance	2,823	2,478
Net income	92	84
Common stock dividends	(44)	(42)
Capital contributions from parent	180	125
Ending balance	3,051
Ending balance	3,051	2,645
WPL [Member] | Common Stock [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	66	66
Ending balance	66	66
WPL [Member] | Additional Paid-in Capital [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,704	1,459
Capital contributions from parent	180	125
Ending balance	1,884	1,584
WPL [Member] | Retained Earnings [Member]
Changes in Shareowners' Equity Roll Forward [Line Items]
Beginning balance	1,053	953
Net income	92	84
Common stock dividends	(44)	(42)
Ending balance	$ 1,101	$ 995