SEGMENT REPORTING, GEOGRAPHIC INFORMATION, AND SIGNIFICANT CUSTOMERS - Summary of Revenues by Geographic Revenue by Country (Detail) - Revenues - Geographic concentration risk	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Concentration risk	100.00%	100.00%	100.00%
Korea
Concentration Risk [Line Items]
Concentration risk	45.00%		18.00%
United States of America
Concentration Risk [Line Items]
Concentration risk	28.00%	77.00%	22.00%
Japan
Concentration Risk [Line Items]
Concentration risk	17.00%		39.00%
Other countries with less than 10% in a year
Concentration Risk [Line Items]
Concentration risk	10.00%	23.00%	21.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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