Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory assets	$ 2,046	$ 1,940
Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	929	934
Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	392	462
Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	160	42
AROs [Member]
Regulatory Assets [Line Items]
Regulatory assets	151	128
Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	84	8
Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	70	92
IPL's DAEC PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	66	90
WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	48	52
Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	146	132
IPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	1,386	1,443
IPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	848	884
IPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	197	228
IPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	1	2
IPL [Member] | AROs [Member]
Regulatory Assets [Line Items]
Regulatory assets	110	89
IPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	48	4
IPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	53	66
IPL [Member] | IPL's DAEC PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	66	90
IPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	63	80
WPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	660	497
WPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	81	50
WPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	195	234
WPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	159	40
WPL [Member] | AROs [Member]
Regulatory Assets [Line Items]
Regulatory assets	41	39
WPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	36	4
WPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	17	26
WPL [Member] | WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	48	52
WPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	$ 83	$ 52