Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 1,208	$ 1,324
Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	572	579
Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	405	398
Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	90	210
Commodity cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	39	40
Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	19	20
WPL's West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	17	32
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	66	45
IPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	676	754
IPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	301	303
IPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	260	259
IPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	48	115
IPL [Member] | Commodity cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	15	38
IPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	14	10
IPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	38	29
WPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	532	570
WPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	271	276
WPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	145	139
WPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	42	95
WPL [Member] | Commodity cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	24	2
WPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	5	10
WPL [Member] | WPL's West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	17	32
WPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 28	$ 16