Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 1,231	$ 1,324
Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	575	579
Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	403	398
Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	117	210
Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	26	20
WPL's West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	24	32
Commodity cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	22	40
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	64	45
IPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	697	754
IPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	302	303
IPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	261	259
IPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	64	115
IPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	19	10
IPL [Member] | Commodity cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	8	38
IPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	43	29
WPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	534	570
WPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	273	276
WPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	142	139
WPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	53	95
WPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	7	10
WPL [Member] | WPL's West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	24	32
WPL [Member] | Commodity cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	14	2
WPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 21	$ 16