TAXES - Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Currently payable -
Federal		$ 14	$ 0	$ 2
State		1	11	21
Currently payable (receivable) Total		15	11	23
Deferred, net -
Federal		279	946	174
State		(24)	47	127
Deferred Tax Total		255	993	301
Investment tax credit amortization		(3)	(4)	(4)
Total income taxes on income from continuing operations	$ 65	267	$ 1,000	320
Federal
Deferred, net -
Income tax expense (benefit), continuing operations, discontinued operations				2
Discontinued Operations, Disposed of by Means Other than Sale \| FES and FENOC \| Federal
Deferred, net -
Federal		$ 21		$ 46

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