INCOME TAXES - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
	Oct. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Long-term asset		$ 103,341	$ 86,090
Withholding and interest for licencing and royalty payments	$ 13,200
Withholding and interest for licencing and royalty payments period	3 years
Current income tax expense		$ 19,262	16,514	$ 8,677
State and foreign income tax returns subject to examination period minimum (in years)		3 years
State and foreign income tax returns subject to examination period maximum (in years)		4 years
Reduction of Korean Withholding Taxes [Member]
Income Taxes [Line Items]
Reduction of deferred tax asset for foreign tax credits and R&D		$ 20,700	20,700
Korean Government [Member]
Income Taxes [Line Items]
Estimated settlement amounts due (refunds) from withholding taxes		(36,900)
U.S.Federal Government [Member]
Income Taxes [Line Items]
Estimated settlement amounts due (refunds) from withholding taxes		16,200
South Korea [Member]
Income Taxes [Line Items]
Current income tax expense		14,900	14,900	$ 14,900
Allocation of Withholding to Non-Korean Patents [Member]
Income Taxes [Line Items]
Long-term asset		40,100	26,900
Allocation of Withholding to Non-Korean Patents [Member] | U.S.Federal Government [Member]
Income Taxes [Line Items]
Estimated settlement amounts due (refunds) from withholding taxes		$ 32,700	$ 25,700