REGULATORY MATTERS (Cost Recovery Mechanisms) (Details) - USD ($)	1 Months Ended			3 Months Ended		6 Months Ended		12 Months Ended
	May 31, 2023	Nov. 30, 2022	Apr. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2025	Dec. 31, 2021	Mar. 31, 2022
Purchased Power and Fuel Adjustment Clause
Public Utilities, General Disclosures [Line Items]
Months approved rate in effect unless modified						12 months
Period of recovery of uncollected true-up balance, approved	12 months		18 months
Forward-looking component of PPFAC rate, approved			$ 0
Regulatory Assets [Roll Forward]
Beginning of Period			$ 102,000,000	$ 118,000,000	$ 102,000,000	$ 124,000,000	$ 91,000,000
Deferred fuel and purchased power costs				65,000,000	88,000,000	123,000,000	153,000,000
PPFAC and Base Power Recoveries				(90,000,000)	(87,000,000)	(154,000,000)	(141,000,000)
End of Period				$ 93,000,000	$ 103,000,000	$ 93,000,000	$ 103,000,000		$ 91,000,000
Renewable Energy Standard
Regulatory Assets [Roll Forward]
Renewable Energy Required Percentage						13.00%
Approved spending budget for the years of 2021 and 2022									$ 66,000,000
Renewable Energy Standard | Scenario, Forecast
Regulatory Assets [Roll Forward]
Renewable energy target percentage								15.00%
Distributed generation requirement percent of target percentage (percentage)								30.00%
Energy Efficiency Standards
Regulatory Assets [Roll Forward]
Approved recovery of spending budget		$ 24,000,000
Annual energy efficiency target, percentage										1.30%
Lost Fixed Cost Recovery
Regulatory Assets [Roll Forward]
Cap on increase in lost fixed cost recovery rate (percentage)						2.00%