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Long-term Contract for Purchase of Electric Power, Buyout Payment

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Carrying amount as of the balance sheet date of capitalized storm costs of a regulated entity that are expected to be recoverable through rate adjustments after one year or beyond the normal operating cycle, if longer.

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Amount of public utility's approved rate increase (decrease) by regulatory agency.

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Amount of public utility's interim rate increase (decrease) allowed while waiting final decision of regulatory agency.

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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

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Regulatory Matters (Narrative) (Details) $ in Millions	1 Months Ended	12 Months Ended
Regulatory Matters (Narrative) (Details) $ in Millions	Aug. 31, 2020 customer	Dec. 31, 2022 USD ($) MW	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Regulatory Matters [Line Items]
Regulatory assets		$ 2,046	$ 1,940
Credits issued to customers		22	(66)	$ (113)
Regulatory liabilities		1,324	1,271
Electric transmission cost recovery [Member]
Regulatory Matters [Line Items]
Regulatory liabilities		20	51
IPL [Member]
Regulatory Matters [Line Items]
Regulatory assets not earning a return		66
Regulatory assets		1,386	1,443
Credits issued to customers		$ 53	1	(20)
Electric capacity of wind farm (in megawatts) \| MW		1,000
Regulatory liabilities		$ 754	691
IPL [Member] \| Electric transmission cost recovery [Member]
Regulatory Matters [Line Items]
Credits issued to customers				42
Regulatory liabilities		10	27
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		28
Regulatory assets		660	497
Credits issued to customers		(31)	(67)	(93)
Regulatory liabilities		570	580
WPL [Member] \| Electric transmission cost recovery [Member]
Regulatory Matters [Line Items]
Regulatory liabilities		10	$ 24
2021 Test Period Fuel-related Costs [Member] \| WPL [Member]
Regulatory Matters [Line Items]
Regulatory assets		37
2022 Test Period Fuel-related Costs [Member] \| WPL [Member]
Regulatory Matters [Line Items]
Regulatory assets		117
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 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
2022 Test Period Retail Electric [Member] \| WPL [Member]
Regulatory Matters [Line Items]
Authorized increase (decrease) in final rates, amount		114
2022 Test Period Retail Gas [Member] \| WPL [Member]
Regulatory Matters [Line Items]
Authorized increase (decrease) in final rates, amount		$ 15
DAEC PPA [Member]
Regulatory Matters [Line Items]
Buyout payment				$ 110
PPA term amendment		5 years