Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Deferred tax liabilities, property	$ 2,389	$ 2,232
Deferred tax liabilities, other	111	101
Total deferred tax liabilities	2,623	2,449
Deferred tax assets, federal credit carryforwards	560	454
Deferred tax assets, net operating losses carryforwards - federal	39	77
Deferred tax assets, net operating losses carryforwards - state	38	37
Deferred tax assets, other	65	73
Subtotal deferred tax assets	702	641
Deferred tax assets, valuation allowances	(6)	(6)
Total deferred tax assets	696	635
Total deferred tax liabilities, net	1,927	1,814
IPL [Member]
Deferred tax liabilities, property	1,416	1,312
Deferred tax liabilities, other	76	83
Total deferred tax liabilities	1,492	1,395
Deferred tax assets, federal credit carryforwards	345	258
Deferred tax assets, net operating losses carryforwards - federal	36	71
Deferred tax assets, net operating losses carryforwards - state	3	1
Deferred tax assets, other	25	30
Subtotal deferred tax assets	409	360
Deferred tax assets, valuation allowances	0	0
Total deferred tax assets	409	360
Total deferred tax liabilities, net	1,083	1,035
WPL [Member]
Deferred tax liabilities, property	913	854
Deferred tax liabilities, other	50	41
Total deferred tax liabilities	963	895
Deferred tax assets, federal credit carryforwards	192	175
Deferred tax assets, net operating losses carryforwards - federal	0	1
Deferred tax assets, net operating losses carryforwards - state	0	0
Deferred tax assets, other	18	18
Subtotal deferred tax assets	210	194
Deferred tax assets, valuation allowances	0	(1)
Total deferred tax assets	210	193
Total deferred tax liabilities, net	753	702
ATC Holdings [Member]
Deferred tax liabilities, ATC Holdings	$ 123	$ 116