NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Taxes) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 463	$ 541
Federal energy credits | Prior to 2013
Regulatory Liabilities [Line Items]
Regulatory liabilities	5	6
Federal energy credits | Since 2013
Regulatory Liabilities [Line Items]
Regulatory liabilities	1	2
Accrued Taxes Other than Income Taxes and Other Liabilities
Other Than Income Taxes Accruals [Line Items]
Deferred deposits	$ 3	$ 7