Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Regulatory Assets [Line Items]
Regulatory assets	$ 2,345	$ 2,261
Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	958	934
Asset retirement obligations (AROs) [Member]
Regulatory Assets [Line Items]
Regulatory assets	408	194
Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	334	347
Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	197	273
Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	95	102
Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	89	120
WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	43	44
IPL's Duane Arnold Energy Center PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	30	42
Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	191	205
IPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	1,548	1,577
IPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	848	831
IPL [Member] | Asset retirement obligations (AROs) [Member]
Regulatory Assets [Line Items]
Regulatory assets	218	160
IPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	165	171
IPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	184	259
IPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	33	34
IPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	2	12
IPL [Member] | IPL's Duane Arnold Energy Center PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	30	42
IPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	68	68
WPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	797	684
WPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	110	103
WPL [Member] | Asset retirement obligations (AROs) [Member]
Regulatory Assets [Line Items]
Regulatory assets	190	34
WPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	169	176
WPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	13	14
WPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	62	68
WPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	87	108
WPL [Member] | WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	43	44
WPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	$ 123	$ 137