CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income	Non- Controlling Interest
Beginning Balances (in shares) at Dec. 31, 2018			102,187,471
Beginning Balances at Dec. 31, 2018	$ 367,257	$ 897	$ 1,022	$ 929,632	$ (562,696)	$ 897	$ (1,440)	$ 739
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax (in shares)			800,818
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	3,363		$ 8	3,355
Issuance of common stock under employee stock purchase plan (in shares)			131,709
Issuance of common stock under employee stock purchase plan	1,139		$ 1	1,138
Issuance of common stock under public offering, net of issuance costs (in shares)			12,650,000
Issuance of common stock under public offering, net of issuance costs	136,308		$ 127	136,181
Acquisition of additional shares of Sangamo France	(321)							(321)
Issuance costs related to Sangamo France Acquisition	(25)			(25)
Stock-based compensation	14,091			14,091
Foreign currency translation adjustment	(4,139)						(4,139)
Net unrealized loss on marketable securities	678						678
Net loss	(99,920)				(99,741)			(179)
Ending Balances (in shares) at Sep. 30, 2019			115,769,998
Ending Balances at Sep. 30, 2019	419,328		$ 1,158	1,084,372	(661,540)		(4,901)	239
Beginning Balances (in shares) at Jun. 30, 2019			115,603,096
Beginning Balances at Jun. 30, 2019	445,748		$ 1,156	1,078,976	(634,233)		(765)	614
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax (in shares)			166,902
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	704		$ 2	702
Issuance of common stock under public offering, net of issuance costs (in shares)
Issuance of common stock under public offering, net of issuance costs	(321)							(321)
Issuance costs related to Sangamo France Acquisition	(7)			(7)
Stock-based compensation	4,701			4,701
Foreign currency translation adjustment	(4,077)						(4,077)
Net unrealized loss on marketable securities	(59)						(59)
Net loss	(27,361)				(27,307)			(54)
Ending Balances (in shares) at Sep. 30, 2019			115,769,998
Ending Balances at Sep. 30, 2019	419,328		$ 1,158	1,084,372	(661,540)		(4,901)	239
Beginning Balances (in shares) at Dec. 31, 2019			115,972,708
Beginning Balances at Dec. 31, 2019	432,739		$ 1,160	1,090,828	(656,985)		(2,449)	185
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax (in shares)			648,660
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	2,468		$ 6	2,462
Issuance of common stock under employee stock purchase plan (in shares)			171,305
Issuance of common stock under employee stock purchase plan	1,187		$ 2	1,185
Issuance of common stock under public offering, net of issuance costs (in shares)			24,420,157
Issuance of common stock under public offering, net of issuance costs	142,526		$ 244	142,282
Acquisition of additional shares of Sangamo France	(660)							(660)
Stock-based compensation	19,066			19,066
Foreign currency translation adjustment	3,989						3,989
Net unrealized loss on marketable securities	13						13
Net loss	(80,447)				(80,392)			(55)
Ending Balances (in shares) at Sep. 30, 2020			141,212,830
Ending Balances at Sep. 30, 2020	520,881		$ 1,412	1,255,823	(737,377)		1,553	(530)
Beginning Balances (in shares) at Jun. 30, 2020			140,973,277
Beginning Balances at Jun. 30, 2020	511,206		$ 1,410	1,247,527	(735,827)		(1,653)	(251)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax (in shares)			239,553
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	1,616		$ 2	1,614
Acquisition of additional shares of Sangamo France	(321)							(321)
Stock-based compensation	6,682			6,682
Foreign currency translation adjustment	3,839						3,839
Net unrealized loss on marketable securities	(633)						(633)
Net loss	(1,508)				(1,550)			42
Ending Balances (in shares) at Sep. 30, 2020			141,212,830
Ending Balances at Sep. 30, 2020	$ 520,881		$ 1,412	$ 1,255,823	$ (737,377)		$ 1,553	$ (530)