ORGANIZATION, BASIS OF PRESENTATION, AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenues from Strategic Partnering Collaboration Agreements and Research Activity Grants (Detail) - Revenue from contract with customer - Customer concentration risk	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Biogen MA, Inc.
Concentration Risk [Line Items]
Percentage of revenues	40.00%	40.00%
Novartis Institutes for BioMedical Research, Inc.
Concentration Risk [Line Items]
Percentage of revenues	32.00%	30.00%
Kite Pharma, Inc.
Concentration Risk [Line Items]
Percentage of revenues	22.00%	24.00%
Sanofi S.A.
Concentration Risk [Line Items]
Percentage of revenues	5.00%	4.00%