Benefit Plans (Accumulated Benefit Obligations) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations	$ 857	$ 1,214
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	857	1,214
Fair value of plan assets	706	1,011
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	875	1,251
Fair value of plan assets	706	1,011
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations	168	210
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	168	210
Fair value of plan assets	83	106
IPL [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations	379	546
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	379	546
Fair value of plan assets	344	462
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	389	567
Fair value of plan assets	344	462
IPL [Member] | Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations	68	84
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	68	84
Fair value of plan assets	58	74
WPL [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations	373	532
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	373	532
Fair value of plan assets	291	450
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	381	546
Fair value of plan assets	291	450
WPL [Member] | Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations	65	81
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations	65	81
Fair value of plan assets	$ 14	$ 17