Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Regulatory Assets [Line Items]
Regulatory assets	$ 2,344	$ 2,046
Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	957	929
Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	378	392
Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	290	70
Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	197	151
Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	145	160
Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	102	84
IPL's Duane Arnold Energy Center PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	54	66
WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	47	48
Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	174	146
IPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	1,648	1,386
IPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	868	848
IPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	190	197
IPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	274	53
IPL [Member] | Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	156	110
IPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	6	1
IPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	41	48
IPL [Member] | IPL's Duane Arnold Energy Center PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	54	66
IPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	59	63
WPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	696	660
WPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	89	81
WPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	188	195
WPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	16	17
WPL [Member] | Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	41	41
WPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	139	159
WPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	61	36
WPL [Member] | WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	47	48
WPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	$ 115	$ 83