Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory assets	$ 2,041	$ 1,940
Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	913	934
Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	436	462
Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	145	128
Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	129	42
Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	102	8
Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	75	92
IPL's DAEC PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	72	90
WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	49	52
Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	120	132
IPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	1,423	1,443
IPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	842	884
IPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	216	228
IPL [Member] | Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	104	89
IPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	2	2
IPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	67	4
IPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	56	66
IPL [Member] | IPL's DAEC PPA amendment [Member]
Regulatory Assets [Line Items]
Regulatory assets	72	90
IPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	64	80
WPL [Member]
Regulatory Assets [Line Items]
Regulatory assets	618	497
WPL [Member] | Tax-related [Member]
Regulatory Assets [Line Items]
Regulatory assets	71	50
WPL [Member] | Pension and OPEB costs [Member]
Regulatory Assets [Line Items]
Regulatory assets	220	234
WPL [Member] | Asset retirement obligations [Member]
Regulatory Assets [Line Items]
Regulatory assets	41	39
WPL [Member] | Commodity cost recovery [Member]
Regulatory Assets [Line Items]
Regulatory assets	127	40
WPL [Member] | Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory assets	35	4
WPL [Member] | Assets retired early [Member]
Regulatory Assets [Line Items]
Regulatory assets	19	26
WPL [Member] | WPL's Western Wisconsin gas distribution expansion investments [Member]
Regulatory Assets [Line Items]
Regulatory assets	49	52
WPL [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory assets	$ 56	$ 52