SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES Geographic Net Revevnues (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Revenues by Geography [Line Items]
Revenues	$ 93,307	$ 110,085	$ 109,482	$ 103,081	$ 108,249	$ 111,255	$ 107,563	$ 104,688	$ 415,955	$ 431,755	$ 389,668
United States of America
Schedule of Revenues by Geography [Line Items]
Revenues									15,315	16,647	14,948
Hong Kong/China
Schedule of Revenues by Geography [Line Items]
Revenues									218,752	227,335	198,858
Taiwan
Schedule of Revenues by Geography [Line Items]
Revenues									43,081	50,307	50,324
Korea
Schedule of Revenues by Geography [Line Items]
Revenues									33,877	38,012	41,996
Western Europe (excluding Germany)
Schedule of Revenues by Geography [Line Items]
Revenues									49,834	48,230	41,214
Japan
Schedule of Revenues by Geography [Line Items]
Revenues									19,897	20,769	19,767
Germany
Schedule of Revenues by Geography [Line Items]
Revenues									14,403	11,558	7,563
Other
Schedule of Revenues by Geography [Line Items]
Revenues									$ 20,796	$ 18,897	$ 14,998