Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 1,363	$ 1,271
Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	573	585
Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	396	384
Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	288	166
WPL's West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	34	36
Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	31	51
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	41	49
IPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	751	691
IPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	308	312
IPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	258	252
IPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	153	77
IPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	11	27
IPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	21	23
WPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	612	580
WPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	265	273
WPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	138	132
WPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	135	89
WPL [Member] | WPL's West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	34	36
WPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	20	24
WPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 20	$ 26