Aggregate additional revenue recognition milestone method revenue achieved.

No definition available.

Name:	sgmo_AggregateAdditionalRevenueRecognitionMilestoneMethodRevenueAchieved
Namespace Prefix:	sgmo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Aggregate additional revenue recognition milestone method revenue eligible to receive.

+ References

No definition available.

+ Details

Name:	sgmo_AggregateAdditionalRevenueRecognitionMilestoneMethodRevenueEligibleToReceive
Namespace Prefix:	sgmo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Collaboration and license agreements number of products approved under agreement.

+ References

No definition available.

+ Details

Name:	sgmo_CollaborationAndLicenseAgreementsNumberOfProductsApprovedUnderAgreement
Namespace Prefix:	sgmo_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Collaboration waiting period expiration date at which time agreement became effective.

+ References

No definition available.

+ Details

Name:	sgmo_CollaborationWaitingPeriodExpirationDateAtWhichTimeAgreementBecameEffective
Namespace Prefix:	sgmo_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Contingent development and sales based milestone payments to be received.

+ References

No definition available.

+ Details

Name:	sgmo_ContingentDevelopmentAndSalesBasedMilestonePaymentsToBeReceived
Namespace Prefix:	sgmo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Milestone payments received.

+ References

No definition available.

+ Details

Name:	sgmo_MilestonePaymentsReceived
Namespace Prefix:	sgmo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Milestone revenue receivable.

+ References

No definition available.

+ Details

Name:	sgmo_MilestoneRevenueReceivable
Namespace Prefix:	sgmo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of clinical or regulatory milestones included in transaction price.

+ References

No definition available.

+ Details

Name:	sgmo_NumberOfClinicalOrRegulatoryMilestonesIncludedInTransactionPrice
Namespace Prefix:	sgmo_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of research program.

+ References

No definition available.

+ Details

Name:	sgmo_NumberOfResearchProgram
Namespace Prefix:	sgmo_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.4(a).Q1)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

+ Details

Name:	us-gaap_DeferredRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Revenue from multiple-deliverable arrangements that include licensing fees and services revenue. Licensing revenue is consideration received from another party for the right to use, but not own, certain of the entity's intangible assets. Licensing arrangements include, but are not limited to, rights to use a patent, copyright, technology, manufacturing process, software or trademark. Licensing fees are generally, but not always, fixed as to amount and not dependent upon the revenue generated by the licensing party. An entity may receive licensing fees for licenses that also generate royalty payments to the entity. Services revenue may be derived by providing other, nonspecified, services during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(d),(e))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_LicenseAndServicesRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of compensation earned (contract income) under a research and development arrangement accounted for as a contract to perform research and development for others.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6420387&loc=d3e23199-108380

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6420387&loc=d3e23221-108380

+ Details

Name:	us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersCompensationEarned
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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

- Definition

The amount of consideration recognized during the period for the milestone or milestones.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 28
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=68058744&loc=SL6892177-166501

+ Details

Name:	us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Revenue earned during the period from the leasing or otherwise lending to a third party the entity's rights or title to certain property. Royalty revenue is derived from a percentage or stated amount of sales proceeds or revenue generated by the third party using the entity's property. Examples of property from which royalties may be derived include patents and oil and mineral rights.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_RoyaltyRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_CounterpartyNameAxis=sgmo_KitePharmaIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis=sgmo_CollaborationAndLicenseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=sgmo_AchievementOfSpecifiedResearchClinicalDevelopmentRegulatoryAndFirstCommercialSaleMilestonesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=sgmo_AchievementOfSpecifiedSalesBasedMilestonesIfAnnualWorldwideNetSalesOfLicensedProductsReachSpecifiedLevelsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=sgmo_PfizerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=sgmo_SBFiveTwoFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=sgmo_OtherProductsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=sgmo_CNineORFSevenTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=sgmo_BioverativIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=sgmo_ShireAgMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Major Customers, Partnerships and Strategic Alliances - Additional Information (Detail)		1 Months Ended						3 Months Ended		12 Months Ended
	Apr. 05, 2018 USD ($)	Apr. 30, 2018 USD ($)	Feb. 28, 2018	Dec. 31, 2017 USD ($)	May 31, 2017 USD ($)	Jan. 31, 2014 USD ($) Program	Jan. 31, 2012 USD ($)	Mar. 31, 2018 USD ($) Product Milestone	Mar. 31, 2017 USD ($)	Dec. 31, 2014 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of research programs \| Program						2
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Collaboration waiting period under HSR expiration date at which time agreement became effective			Apr. 05, 2018
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member] \| Subsequent Event [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments received		$ 150,000,000
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member] \| Maximum [Member] \| Subsequent Event [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contingent development - and sales-based milestone payments to be received	$ 3,010,000,000
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member] \| Achievement of Specified Research, Clinical Development, Regulatory and First Commercial Sale Milestones [Member] \| Subsequent Event [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contingent development - and sales-based milestone payments to be received	1,260,000,000
Kite Pharma, Inc. ("Kite") [Member] \| Collaboration and License Agreement [Member] \| Achievement of Specified Sales-based Milestones if Annual Worldwide Net Sales of Licensed Products Reach Specified Levels [Member] \| Subsequent Event [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contingent development - and sales-based milestone payments to be received	$ 1,750,000,000
Pfizer [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments received								$ 0
Revenues under agreement					$ 70,000,000
Potential amount eligible to receive for certain milestones					208,500,000
Milestone revenue receivable					475,000,000
Number of products approved \| Product								0
Royalty revenues								$ 0
Deferred revenue								40,100,000
Recognition of upfront fee								$ 7,700,000
Pfizer [Member] \| SB-525 [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential amount to be funded for achievement of specified commercialized and sales milestones					266,500,000
Number of milestones included in transaction price \| Milestone								0
Pfizer [Member] \| SB-525 [Member] \| Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone revenue receivable					300,000,000
Pfizer [Member] \| Other Products [Member] \| Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone revenue receivable					$ 175,000,000
Pfizer [Member] \| C9ORF72 [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues under agreement				$ 12,000,000
Number of milestones included in transaction price \| Milestone								0
Deferred revenue								$ 11,500,000
Recognition of upfront fee								500,000
Pfizer [Member] \| C9ORF72 [Member] \| Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential amount eligible to receive for certain milestones				60,000,000
Potential amount to be funded for achievement of specified commercialized and sales milestones				90,000,000
Bioverativ Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments received								0
Revenues under agreement						$ 20,000,000		$ 75,700,000
Potential amount eligible to receive for certain milestones						115,800,000
Potential amount to be funded for achievement of specified commercialized and sales milestones						$ 160,500,000
Number of products approved \| Product								0
Royalty revenues								$ 0
Number of milestones included in transaction price \| Milestone								0
Deferred revenue								$ 7,500,000
Recognition of upfront fee								$ 1,154,000	$ 442,000
Shire AG [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues under agreement							$ 13,000,000
Deferred revenue				$ 2,300,000
Recognition of upfront fee									$ 583,000
Recognition of milestone										$ 1,000,000