Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory assets	$ 2,051	$ 1,940
Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	954	934
Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	445	462
Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	140	128
Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	101	8
Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	88	42
Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	82	92
IPL's DAEC PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	78	90
WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	50	52
Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	113	132
IPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	1,490	1,443
IPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	903	884
IPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	220	228
IPL [Member] | Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	99	89
IPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	69	4
IPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	2	2
IPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	61	66
IPL [Member] | IPL's DAEC PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	78	90
IPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	58	80
WPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	561	497
WPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	51	50
WPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	225	234
WPL [Member] | Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	41	39
WPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	32	4
WPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	86	40
WPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	21	26
WPL [Member] | WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	50	52
WPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	$ 55	$ 52