TAX CREDITS RECEIVABLE, NET - Summary of Changes in Carrying Value of Tax Credits Receivable, Net (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Tax Credit Receivable Net [Abstract]
Balance at beginning of year	$ 12,104	$ 13,198
Returned to State of Alaska	(9,396)	0
Balance at end of period	$ 2,708	$ 13,198