TAXES - Narrative (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Feb. 27, 2020	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes (Textuals) [Abstract]
Excess deferred tax amortization due to the Tax Act			$ (54)	$ (56)	$ (74)
Effective income tax rate (percent)			20.50%	11.20%	19.10%
Nondeductible DPA monetary penalty			$ 52	$ 0	$ 0
Decrease in amortization benefit				10
TMI-2 reversal of tax regulatory liabilities			0	40	0
Unrecognized tax benefits from worthless stock deduction	$ 316		81
Federal tax credits claimed			34	0	0
Operating loss carryforwards, subject to expiration			6,900
Operating loss carryforwards, subject to expiration, net of tax			1,500
Operating loss carryforwards, not subject to expiration			11,900
Operating loss carryforwards, not subject to expiration, net of tax			544
Pre-tax net operating loss carryforwards expected to utilized			2,700
Operating loss carryforwards expected to utilized, net of tax			136
Unrecognized tax benefits			47	139	164	$ 158
Decrease in unrecognized tax benefits			92
Decrease resulting from change in worthless stock deduction			68
Decrease resulting from nondeductible interest			29
Decreases resulting from prior positions			8	28	12
Decrease from tax rate changes			1
Decrease for lapse in statute			2	$ 2	$ 4
Increase resulting related to federal positions			15
Unrecognized tax benefits that would impact future tax rates			39
Unrecognized tax benefits, portion expected to be resolved in the next fiscal year			31
Unrecognized tax benefits that would impact effective tax rate			24
West Virginia
Income Taxes (Textuals) [Abstract]
Decreases resulting from prior positions			7
State and Local | West Virginia
Income Taxes (Textuals) [Abstract]
Excess deferred tax amortization due to the Tax Act		$ 9	9
FES
Income Taxes (Textuals) [Abstract]
Nondeductible DPA monetary penalty			$ 52