INCOME TAXES - Reconciliation of Federal Income Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Income before income taxes	$ 400	$ 371
Federal income tax expense at statutory rate (21%)	84	78
Increases (reductions) in tax expense resulting from:
State income taxes, net of federal tax benefit	14	26
AFUDC equity and other flow-through	(5)	(8)
Excess deferred tax amortization due to the Tax Act	(16)	(15)
Valuation allowances	9	34
Remeasurement of state deferred taxes	0	(26)
Other, net	4	(6)
Total income taxes	$ 90	$ 83
Effective income tax rate	22.50%	22.40%