INCOME TAXES (Additional Information) (Details) - USD ($)		12 Months Ended
	Feb. 02, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Excess deferred income taxes		$ 14,000,000	$ 7,000,000	$ 9,000,000
Valuation allowance		0	0
Unrecognized tax benefits, if recognized, decrease in income tax expense (benefit)		1,000,000	1,000,000
Interest expense related to uncertain tax position		0	0
Interest payable		0	0
Penalties accrued		0	0
Decrease in uncertain tax position obligations	$ 18,000,000	18,000,000	0
Income taxes paid, net		0	(14,000,000)	(14,000,000)
UNS Energy | Federal
Operating Loss Carryforwards [Line Items]
Income taxes paid, net		$ 7,000,000
Proceeds from income tax refunds			10,000,000	$ 14,000,000
Current Assets—Other
Operating Loss Carryforwards [Line Items]
AMT credit			$ 14,000,000