EMPLOYEE BENEFIT PLANS - Postretirement Benefits Other than Pensions, Actuarial Gains and Losses, and Assumptions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Executive Benefit Restoration Plan
Net unrecognized actuarial gains and losses related to the postretirement medical benefit obligation are included in accumulated other comprehensive income
Amounts included in accumulated other comprehensive income at beginning of period	$ (2,105)	$ (4,932)
Plan amendments - prior service cost	0	(308)	$ (1,050)
Amortization of prior service credit into other income	1,156	1,156	1,113
Amortization of actuarial (gain) loss	219	426	515
Curtailment and settlement	0	(187)	141
Unrecognized actuarial gain (loss)	(909)	1,740	(778)
Amounts included in accumulated other comprehensive income at end of period	(1,639)	(2,105)	(4,932)
Postretirement Medical Benefit Plans
Net unrecognized actuarial gains and losses related to the postretirement medical benefit obligation are included in accumulated other comprehensive income
Amounts included in accumulated other comprehensive income at beginning of period	2,078	3,580
Plan amendments - prior service cost	0	0	5,698
Amortization of prior service credit into other income	(1,637)	(1,636)	(2,139)
Amortization of actuarial (gain) loss	(84)	102	78
Unrecognized actuarial gain (loss)	757	32	784
Plan amendments	0	0
Amounts included in accumulated other comprehensive income at end of period	$ 1,114	$ 2,078	$ 3,580
Assumptions used
Weighted-average discount rate (as a percent)	5.01%
Initial health care cost trend (2018) (as a percent)	7.25%
Ultimate health care cost trend (as a percent)	4.50%
Year that the rate reached the ultimate health care cost trend rate	2034
Average remaining service lives of active plan participants (years)	2 years 7 months 9 days