CONCENTRATION OF RISK - Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Concentration Risk [Line Items]
Revenues	$ 129,660	$ 57,968	$ 263,660	$ 170,245
South Korea [Member]
Concentration Risk [Line Items]
Revenues	86,324	31,062	154,299	100,487
China [Member]
Concentration Risk [Line Items]
Revenues	36,308	20,508	96,812	58,342
Japan [Member]
Concentration Risk [Line Items]
Revenues	2,001	2,197	3,316	3,984
Other Non-U.S. Locations [Member]
Concentration Risk [Line Items]
Revenues	895	315	1,720	812
Total Non-U.S. Locations [Member]
Concentration Risk [Line Items]
Revenues	125,528	54,082	256,147	163,625
United States [Member]
Concentration Risk [Line Items]
Revenues	$ 4,132	$ 3,886	$ 7,513	$ 6,620