Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Deferred tax liabilities, property	$ 2,596	$ 2,453
Deferred tax liabilities, other	178	213
Total deferred tax liabilities	2,909	2,793
Deferred tax assets, federal credit carryforwards	605	649
Deferred tax assets, net operating losses carryforwards - state	20	26
Deferred tax assets, other	98	79
Subtotal deferred tax assets	723	754
Deferred tax assets, valuation allowances	(2)	(3)
Total deferred tax assets	721	751
Total deferred tax liabilities, net	2,188	2,042
IPL [Member]
Deferred tax liabilities, property	1,521	1,415
Deferred tax liabilities, other	120	157
Total deferred tax liabilities	1,641	1,572
Deferred tax assets, federal credit carryforwards	426	449
Deferred tax assets, net operating losses carryforwards - state	1	1
Deferred tax assets, other	37	32
Subtotal deferred tax assets	464	482
Deferred tax assets, valuation allowances	(2)	(1)
Total deferred tax assets	462	481
Total deferred tax liabilities, net	1,179	1,091
WPL [Member]
Deferred tax liabilities, property	999	972
Deferred tax liabilities, other	66	64
Total deferred tax liabilities	1,065	1,036
Deferred tax assets, federal credit carryforwards	166	191
Deferred tax assets, net operating losses carryforwards - state	0	0
Deferred tax assets, other	34	19
Subtotal deferred tax assets	200	210
Deferred tax assets, valuation allowances	0	(1)
Total deferred tax assets	200	209
Total deferred tax liabilities, net	865	827
ATC Holdings [Member]
Deferred tax liabilities, ATC Holdings	135	127
ATC Holdings [Member] | IPL [Member]
Deferred tax liabilities, ATC Holdings	0	0
ATC Holdings [Member] | WPL [Member]
Deferred tax liabilities, ATC Holdings	$ 0	$ 0