INCOME TAXES - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax asset:
Capitalized research expenditures	$ 39,459	$ 38,485
Retirement plan	12,555	13,495
Tax credit carry forwards	8,938	8,100
Accruals and reserves	7,180	6,944
Lease liabilities	6,671	7,230
Deferred revenue	1,741	2,077
Stock-based compensation	1,498	1,454
Other	1,362	3,400
Valuation allowance	(9,551)	(11,087)
Deferred Tax Assets, Gross	79,404	81,185
Deferred tax assets	69,853	70,098
Deferred tax liability:
Lease Assets	6,302	6,944
Acquisition Goodwill	(1,549)	(1,283)
Other	(2,894)	(3,710)
Deferred tax liabilities	(10,745)	(11,937)
Net deferred tax assets	$ 59,108	$ 58,161