INCOME TAXES - Reconciliation of Statutory Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Statutory income tax	$ 21,344	$ 22,065	$ 22,858
Increase (reduction) in taxes due to:
State income taxes net of federal tax benefit	7,383	7,334	7,598
Effect of regulatory treatment of fixed asset differences	(6,274)	(6,327)	(9,201)
Investment tax credits	(74)	(74)	(74)
AFUDC equity	(1,155)	(891)	(1,392)
Stock based stock compensation	455	791	523
TCJA refund	(13,919)	(19,417)	(9,470)
Other	(1,385)	611	1,176
Total income tax	$ 6,375	$ 4,092	$ 12,018

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