INVESTMENT SECURITIES - Summary of investment securities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Amortized cost, as adjusted	$ 47,896	$ 71,778
Gross unrealized holding losses	579	1,482
Estimated fair value	47,317	70,296
Short-term Investments [Member] | Obligations of domestic governmental agencies [Member]
Amortized cost, as adjusted	47,896	59,374
Gross unrealized holding losses	579	1,053
Estimated fair value	$ 47,317	58,321
Long-term investments [Member] | Obligations of domestic governmental agencies [Member]
Amortized cost, as adjusted		12,404
Gross unrealized holding losses		429
Estimated fair value		$ 11,975