CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenues	$ 26,280,000	$ 13,076,000
Operating expenses:
Research and development	56,434,000	41,479,000
General and administrative	16,148,000	16,119,000
Total operating expenses	72,582,000	57,598,000
Loss from operations	(46,302,000)	(44,522,000)
Interest and other income, net	625,000	1,548,000
Loss before taxes	(45,677,000)	(42,974,000)
Income tax expense	262,000	0
Net loss	(45,939,000)	(42,974,000)
Net loss attributable to non-controlling interest	(6,000)	(61,000)
Net loss attributable to Sangamo Therapeutics, Inc. stockholders	$ (45,933,000)	$ (42,913,000)
Basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders (in dollars per share)	$ (0.32)	$ (0.37)
Shares used in computing basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders (in shares)	143,112	116,060