OTHER DEFERRED CREDITS AND OTHER LIABILITIES - Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Deferred Credits and Other Liabilities [Abstract]
Transmission easements	$ 18,770	$ 17,862
OATT deposits	52,348	27,872
Financial liabilities - reclamation	11,337	16,895
Customer deposits	16,179	12,091
Contract liabilities (unearned revenue) - noncurrent	3,121	3,125
Lease liabilities - noncurrent	5,703	1,396
Other	6,618	4,884
Total other deferred credits and other liabilities	$ 114,076	$ 84,125