Income Taxes (Schedule Of Components Of Income Tax) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Current tax expense (benefit):
Federal	$ 10	$ 13	$ (3)
State	(1)	(10)	(6)
Deferred tax expense (benefit):
Federal	59	60	100
State	33	15	36
Production tax credits	(208)	(177)	(121)
Investment tax credits	(42)	(15)	(1)
Provision recorded as a change in accrued interest	0	0	(1)
Income tax expense (benefit)	(149)	(114)	4
IPL [Member]
Current tax expense (benefit):
Federal	(21)	(19)	(44)
State	(10)	(19)	(21)
Deferred tax expense (benefit):
Federal	36	38	87
State	2	(17)	17
Production tax credits	(133)	(108)	(95)
Investment tax credits	(1)	(4)	(1)
Provision recorded as a change in accrued interest	0	0	(1)
Income tax expense (benefit)	(127)	(129)	(58)
WPL [Member]
Current tax expense (benefit):
Federal	38	37	48
State	18	23	25
Deferred tax expense (benefit):
Federal	30	24	10
State	16	7	3
Production tax credits	(75)	(69)	(26)
Investment tax credits	(41)	(11)	0
Provision recorded as a change in accrued interest	0	0	0
Income tax expense (benefit)	$ (14)	$ 11	$ 60