Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Deferred tax liabilities, property	$ 2,442	$ 2,389
Deferred tax liabilities, other	155	111
Total deferred tax liabilities	2,722	2,623
Deferred tax assets, federal credit carryforwards	672	560
Deferred tax assets, net operating losses carryforwards - federal	0	39
Deferred tax assets, net operating losses carryforwards - state	32	38
Deferred tax assets, other	75	65
Subtotal deferred tax assets	779	702
Deferred tax assets, valuation allowances	0	(6)
Total deferred tax assets	779	696
Total deferred tax liabilities, net	1,943	1,927
IPL [Member]
Deferred tax liabilities, property	1,440	1,416
Deferred tax liabilities, other	86	76
Total deferred tax liabilities	1,526	1,492
Deferred tax assets, federal credit carryforwards	450	345
Deferred tax assets, net operating losses carryforwards - federal	0	36
Deferred tax assets, net operating losses carryforwards - state	0	3
Deferred tax assets, other	29	25
Subtotal deferred tax assets	479	409
Deferred tax assets, valuation allowances	0	0
Total deferred tax assets	479	409
Total deferred tax liabilities, net	1,047	1,083
WPL [Member]
Deferred tax liabilities, property	938	913
Deferred tax liabilities, other	80	50
Total deferred tax liabilities	1,018	963
Deferred tax assets, federal credit carryforwards	209	192
Deferred tax assets, net operating losses carryforwards - federal	0	0
Deferred tax assets, net operating losses carryforwards - state	0	0
Deferred tax assets, other	20	18
Subtotal deferred tax assets	229	210
Deferred tax assets, valuation allowances	0	0
Total deferred tax assets	229	210
Total deferred tax liabilities, net	789	753
ATC Holdings [Member]
Deferred tax liabilities, ATC Holdings	125	123
ATC Holdings [Member] | IPL [Member]
Deferred tax liabilities, ATC Holdings	0	0
ATC Holdings [Member] | WPL [Member]
Deferred tax liabilities, ATC Holdings	$ 0	$ 0