SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Restricted assets	$ 985	$ 1,619
Prepaid pension costs	46,725	45,292
Other assets	38,989	37,418
Total other assets	$ 86,699	$ 84,329