INCOME TAXES - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
	Oct. 30, 2018	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2018
Income Taxes [Line Items]
Effective income tax rate (benefit) expense, percent		18.90%	18.60%
Income tax expense (benefit)		$ 12,063	$ 8,700
Long-term asset		$ 106,704		$ 103,341
Withholding and interest for licencing and royalty payments	$ 13,200
Withholding and interest for licencing and royalty payments period	3 years
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
U.S.Federal Government [Member]
Income Taxes [Line Items]
Estimated settlement amounts due (refunds) from withholding taxes					$ 16,200
Korean Government [Member]
Income Taxes [Line Items]
Estimated settlement amounts due (refunds) from withholding taxes					$ (36,900)
Allocation of Withholding to Non-Korean Patents [Member]
Income Taxes [Line Items]
Long-term asset		43,400		40,100
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		$ 35,900		$ 32,700