CAPITALIZATION - Narrative (Details)				2 Months Ended	3 Months Ended								12 Months Ended
	Jan. 10, 2023 USD ($)	Dec. 13, 2022 USD ($) $ / shares	Nov. 06, 2021 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Sep. 30, 2022 $ / shares	Jun. 30, 2022 $ / shares	Mar. 31, 2022 $ / shares	Dec. 31, 2021 USD ($) $ / shares shares	Sep. 30, 2021 $ / shares	Jun. 30, 2021 $ / shares	Mar. 31, 2021 $ / shares	Dec. 31, 2022 USD ($) subsidiary $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 $ / shares shares	Nov. 29, 2022 USD ($)	Jun. 30, 2013 USD ($)
Debt Instrument [Line Items]
Retained earnings (accumulated deficit)				$ (1,605,000,000)	$ (1,199,000,000)				$ (1,605,000,000)				$ (1,199,000,000)	$ (1,605,000,000)
Dividends declared (in dollars per share) | $ / shares		$ 0.39											$ 1.56	$ 1.56	$ 1.56
Common stock dividends per share paid, in dollars per share | $ / shares					$ 0.39	$ 0.39	$ 0.39	$ 0.39	$ 0.39	$ 0.39	$ 0.39	$ 0.39
FERC-defined equity to total capitalization ratio													35.00%
Common stock, par value (in dollars per share) | $ / shares				$ 0.10	$ 0.10				$ 0.10				$ 0.10	$ 0.10
Preferred shares, outstanding (in shares) | shares				0	0				0				0	0
Preference shares outstanding (in shares) | shares				0	0				0				0	0
Number of subsidiaries that issued environmental control bonds | subsidiary													2
Environmental control bonds outstanding				$ 274,000,000	$ 247,000,000				$ 274,000,000				$ 247,000,000	$ 274,000,000
Principal default amount specified in debt covenants													100,000,000
Phase In Recovery Bonds
Debt Instrument [Line Items]
Long-term debt and other long-term obligations				222,000,000	$ 206,000,000				$ 222,000,000				$ 206,000,000	$ 222,000,000
Common Stock Purchase Agreement
Debt Instrument [Line Items]
Number of shares issued in transaction | shares			25,588,535
Common stock, par value (in dollars per share) | $ / shares			$ 0.10
Sale of stock, price per share (in dollars per share) | $ / shares			$ 39.08
Investment amount			$ 1,000,000,000
Transaction costs				$ 26,000,000
Registered Shareholders, Directors and Employees of Subsidiaries
Debt Instrument [Line Items]
Share-based benefit plans (in shares) | shares													2,000,000	1,000,000	2,000,000
Ohio Funding Companies | Phase In Recovery Bonds
Debt Instrument [Line Items]
Face amount of loan																	$ 445,000,000
AGC
Debt Instrument [Line Items]
FERC-defined equity to total capitalization ratio													45.00%
WP | 5.29% First Mortgage Bond Due 2033 | First Mortgage Bond
Debt Instrument [Line Items]
Face amount of loan																$ 300,000,000
Proceeds from issuance of FMB's		$ 250,000,000
Interest Rate																5.29%
WP | 5.29% First Mortgage Bond Due 2033 | First Mortgage Bond | Subsequent Event
Debt Instrument [Line Items]
Proceeds from issuance of FMB's	$ 50,000,000