INCOME TAXES - Reconciliation of Federal Income Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Tax Disclosure [Abstract]
Income before income taxes	$ 328	$ 241	$ 728	$ 612
Income before income taxes			728	612
Federal income tax expense at statutory rate (21%)	69	51	153	129
Increases (reductions) in tax expense resulting from:
State income taxes, net of federal tax benefit	19	17	43	44
AFUDC equity and other flow-through	(4)	(7)	(9)	(14)
Excess deferred tax amortization due to the Tax Act	(16)	(15)	(32)	(31)
Valuation allowances	0	0	0	34
Remeasurement of state deferred taxes	0	0	0	(26)
Other, net	6	3	9	(4)
Total income taxes	$ 74	$ 49	$ 164	$ 132
Effective income tax rate	22.60%	20.30%	22.50%	21.60%