Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenues	$ 17,548	$ 21,416	$ 25,619	$ 34,053
Operating expenses:
Research and development	36,455	29,255	71,305	52,802
General and administrative	14,597	11,301	31,715	21,388
Total operating expenses	51,052	40,556	103,020	74,190
Loss from operations	(33,504)	(19,140)	(77,401)	(40,137)
Interest and other income, net	3,148	2,500	4,842	3,310
Net loss	(30,356)	(16,640)	(72,559)	(36,827)
Net loss attributable to non-controlling interest	(72)	0	(125)	0
Net loss to Sangamo Therapeutics, Inc. stockholders	$ (30,284)	$ (16,640)	$ (72,434)	$ (36,827)
Basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders (in USD per share)	$ (0.26)	$ (0.17)	$ (0.67)	$ (0.40)
Shares used in computing basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders (in shares)	114,382	97,267	108,360	91,831