CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenues	$ 28,563	$ 57,763	$ 82,715	$ 92,392
Operating expenses:
Research and development	62,498	45,287	179,018	128,289
General and administrative	14,501	16,177	47,135	50,223
Total operating expenses	76,999	61,464	226,153	178,512
Loss from operations	(48,436)	(3,701)	(143,438)	(86,120)
Interest and other income, net	834	2,430	3,010	5,910
Loss before taxes	(47,602)	(1,271)	(140,428)	(80,210)
Income tax expense	86	237	373	237
Net loss	(47,688)	(1,508)	(140,801)	(80,447)
Net income (loss) attributable to non-controlling interest	0	42	(11)	(55)
Net loss attributable to Sangamo Therapeutics, Inc. stockholders	$ (47,688)	$ (1,550)	$ (140,790)	$ (80,392)
Earnings per share, basic (in dollars per share)	$ (0.33)	$ (0.01)	$ (0.98)	$ (0.61)
Earnings per share, diluted (in dollars per share)	$ (0.33)	$ (0.01)	$ (0.98)	$ (0.61)
Shares used in computing basic net loss per share attributable to Sangamo Therapeutics, Inc. stockholders (in shares)	145,399	141,100	144,173	132,079
Shares used in computing diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders (in shares)	145,399	141,100	144,173	132,079