FAIR VALUE MEASUREMENTS - Narrative (Detail) - USD ($) $ in Thousands		2 Months Ended	3 Months Ended		6 Months Ended			12 Months Ended
	Oct. 01, 2018	Nov. 23, 2018	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Jul. 20, 2018
Debt Securities, Available-for-sale [Line Items]
Purchase of additional Sangamo France shares					$ 237	$ 0
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)			117,000	111,000			25,047,671		111,000
Purchase of additional Sangamo France shares					200
Number of free shares outstanding subject to purchase (in shares)			249,000
Value of shares repurchased					100
Sangamo France | Share Purchase Agreement and Tender Offer Agreement | Forecast
Debt Securities, Available-for-sale [Line Items]
Purchase of additional Sangamo France shares								$ 300
Tx Cell S A [Member] | Share Purchase Agreement and Tender Offer Agreement
Debt Securities, Available-for-sale [Line Items]
Increase in fair value of the free shares					$ 100