SEGMENT REPORTING, GEOGRAPHIC INFORMATION, AND SIGNIFICANT CUSTOMERS - Summary of Geographic Revenue as Percentage of Total Revenues by Country (Detail) - Net Revenues - Geographic Concentration Risk	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Concentration risk	100.00%	100.00%	100.00%
United States of America
Concentration Risk [Line Items]
Concentration risk	77.00%	22.00%	26.00%
Japan
Concentration Risk [Line Items]
Concentration risk		39.00%	11.00%
Korea
Concentration Risk [Line Items]
Concentration risk		18.00%	47.00%
Other countries with less than 10% in a year
Concentration Risk [Line Items]
Concentration risk	23.00%	21.00%	16.00%