Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

No definition available.

Name:	us-gaap_BusinessAcquisitionSharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Value of input used to measure derivative liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_DerivativeLiabilityMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Foreign exchange rate used to translate amounts denominated in functional currency to reporting currency.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6897108&loc=SL6897125-166521

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6450520&loc=d3e32618-110901

+ Details

Name:	us-gaap_ForeignCurrencyExchangeRateTranslation1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

+ Details

Name:	us-gaap_SharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Value of input used to measure outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur.

+ References

+ Details

Name:	us-gaap_WarrantsAndRightsOutstandingMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputSharePriceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputOptionVolatilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPriceVolatilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=sgmo_SangamoFranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=sgmo_MeasurementInputStockPriceCorrelationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Fair Value Measurement - Summary of Estimated Fair Value of Free Share Liability Assumptions (Detail)	Dec. 31, 2020 $ / shares	Dec. 31, 2020 € / shares	Dec. 31, 2019 $ / shares	Dec. 31, 2019 € / shares	Oct. 01, 2018 $ / shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
EUR/ USD exchange rate	0.82	0.82	0.91	0.91
Measurement Input, Share Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sangamo Stock Price (USD) (in dollars per share)	$ 15.61		$ 8.68
Stock Price Volatility Estimate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Volatility Estimate	0.889	0.889	0.725	0.725
Exchange Rate Volatility Estimate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Volatility Estimate	0.063	0.063	0.066	0.066
TxCell S.A.
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sangamo France Stock Price (EUR) (in Euro per share)					$ 2.99
TxCell S.A. \| Measurement Input, Share Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sangamo France Stock Price (EUR) (in Euro per share) \| € / shares		€ 3.85		€ 2.14
TxCell S.A. \| Measurement Input Stock Price Correlation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Estimated correlation Sangamo and Sangamo France stock prices	1.000	1.000	1.000	1.000
TxCell S.A. \| Stock Price Volatility Estimate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Volatility Estimate	0.889	0.889	0.725	0.725