Regulatory Matters (Narrative) (Details) $ in Millions	1 Months Ended		12 Months Ended
	Sep. 30, 2020 USD ($)	Aug. 31, 2020 customer	Dec. 31, 2021 USD ($) MW	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Regulatory Matters [Line Items]
Regulatory assets			$ 1,940	$ 2,010
Credits issued to customers			(66)	(113)	$ (40)
Regulatory liabilities			1,271	1,306
Electric transmission cost recovery [Member]
Regulatory Matters [Line Items]
Regulatory liabilities			51	68
IPL [Member]
Regulatory Matters [Line Items]
Regulatory assets not earning a return			75
Regulatory assets			1,443	1,483
Credits issued to customers			$ 1	(20)	2
Electric capacity of wind farm (in megawatts) | MW			1,000
Regulatory liabilities			$ 691	676
IPL [Member] | Electric transmission cost recovery [Member]
Regulatory Matters [Line Items]
Credits issued to customers				42
Regulatory liabilities			27	39
IPL [Member] | Derecho windstorm [Member]
Regulatory Matters [Line Items]
Number of customers without power, derecho windstorm (number of customers) | customer		250,000
Derecho windstorm repair and rebuilding costs			140
Net regulatory liability, derecho windstorm			8
WPL [Member]
Regulatory Matters [Line Items]
Regulatory assets not earning a return			13
Regulatory assets			497	527
Credits issued to customers			(67)	(93)	(42)
Regulatory liabilities			580	630
WPL [Member] | Electric transmission cost recovery [Member]
Regulatory Matters [Line Items]
Regulatory liabilities			24	29
2020 Test Period Retail Electric [Member] | IPL [Member]
Regulatory Matters [Line Items]
Interim rate increase (decrease), amount					$ 90
Authorized increase (decrease) in final rates, amount				127
2020 Test Period Retail Electric [Member] | IPL [Member] | Tax-related [Member]
Regulatory Matters [Line Items]
Regulatory liabilities				27
2020 Test Period Retail Electric [Member] | IPL [Member] | Revenue subject to refund [Member]
Regulatory Matters [Line Items]
Regulatory liabilities				8
2020 Test Period Retail Electric [Member] | WPL [Member]
Regulatory Matters [Line Items]
Authorized increase (decrease) in final rates, amount				$ 29
Authorized increase (decrease) in final rates, percentage				2.00%
2020 Test Period Retail Gas [Member] | IPL [Member]
Regulatory Matters [Line Items]
Authorized increase (decrease) in final rates, amount				$ 12
2019 Test Period Retail Electric [Member] | WPL [Member] | Revenue subject to refund [Member]
Regulatory Matters [Line Items]
Credits issued to customers				$ 12
Deferred Fuel Costs | WPL [Member]
Regulatory Matters [Line Items]
Regulatory assets			$ 37
DAEC PPA [Member]
Regulatory Matters [Line Items]
Buyout payment	$ 110
PPA term amendment			5 years