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FAIR VALUE MEASUREMENTS - Narrative (Detail) - USD ($)
$ in Thousands
 2 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Oct. 01, 2018
Nov. 23, 2018
Sep. 30, 2020
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2019
Jul. 20, 2018
Debt Securities, Available-for-sale [Line Items]                
Purchase of additional Sangamo France shares       $ 503 $ 262      
Sangamo France                
Debt Securities, Available-for-sale [Line Items]                
Number of shares acquired (in shares) 13,519,036 11,528,635            
Sangamo France | Share Purchase Agreement and Tender Offer Agreement                
Debt Securities, Available-for-sale [Line Items]                
Number of free shares held by the holders (in shares)               477,000
Estimated fair value liability of free shares             $ 200 $ 200
Number of shares acquired (in shares)       228,000   25,047,671 111,000  
Purchase of additional Sangamo France shares       $ 500     $ 300  
Number of free shares outstanding subject to purchase (in shares)     138,000          
Value of shares repurchased       $ 100