INCOME TAXES, Deferred Income Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets [Abstract]
State tax credits	$ 1,000	$ 1,033
Unfunded pension liability	605	1,139
Reserves and accruals	2,483	2,828
Federal, state and foreign net operating loss credit carryforwards	8,370	10,524
Depreciation	850	917
Other accruals	5,641	4,915
Total deferred tax assets	18,949	21,356
Deferred tax liabilities [Abstract]
Depreciation	1,666	989
Amortization	7,930	8,490
Other accruals	893	946
Total deferred tax liabilities	10,489	10,425
Valuation allowance	9,200	8,343
Net deferred tax assets		$ 2,588
Net deferred tax liabilities	$ (740)