Sangamo Therapeutics (SGMO) 10-Q 6 Nov 19 2019 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2019	Nov. 01, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	000-30171
Entity Registrant Name	SANGAMO THERAPEUTICS, INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	68-0359556
Entity Address, Address Line One	501 Canal Boulevard
Entity Address, City or Town	Richmond
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94804
City Area Code	510
Local Phone Number	970-6000
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	SGMO
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		115,937,618
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001001233
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 114,291	$ 140,418
Restricted cash, current portion	2,000	0
Marketable securities	240,561	259,715
Interest receivable	680	375
Accounts receivable	21,953	4,673
Prepaid expenses and other current assets	4,691	5,340
Total current assets	384,176	410,521
Marketable securities, non-current	52,789	0
Property and equipment, net	26,516	78,723
Intangible assets	51,741	54,243
Goodwill	38,270	40,044
Operating lease right-of-use assets	77,505
Other non-current assets	7,725	3,364
Non-current restricted cash	1,500	3,500
Total assets	640,222	590,395
Current liabilities:
Accounts payable and accrued liabilities	21,965	21,457
Accrued compensation and employee benefits	11,024	9,490
Deferred revenues	47,561	47,564
Total current liabilities	80,550	78,511
Deferred revenues, non-current	87,798	108,273
Long-term portion of lease liabilities	40,609	27,689
Deferred income tax	6,395	6,705
Other non-current liabilities	5,542	1,960
Total liabilities	220,894	223,138
Commitments and contingencies
Stockholders' equity:
Common stock	1,158	1,022
Additional paid-in capital	1,084,372	929,632
Accumulated deficit	(661,540)	(562,696)
Accumulated other comprehensive loss	(4,901)	(1,440)
Total Sangamo Therapeutics, Inc. stockholders' equity	419,089	366,518
Non-controlling interest	239	739
Total stockholders' equity	419,328	367,257
Total liabilities and stockholders' equity	$ 640,222	$ 590,395

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenues	$ 21,958	$ 23,562	$ 47,577	$ 57,615
Operating expenses:
Research and development	36,288	28,810	107,593	81,612
General and administrative	14,918	10,993	46,633	32,381
Total operating expenses	51,206	39,803	154,226	113,993
Loss from operations	(29,248)	(16,241)	(106,649)	(56,378)
Interest and other income, net	1,887	3,398	6,729	6,708
Net loss	(27,361)	(12,843)	(99,920)	(49,670)
Net loss attributable to non-controlling interest	(54)	0	(179)	0
Net loss to Sangamo Therapeutics, Inc. stockholders	$ (27,307)	$ (12,843)	$ (99,741)	$ (49,670)
Basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders (in USD per share)	$ (0.24)	$ (0.13)	$ (0.90)	$ (0.52)
Shares used in computing basic and diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders (in shares)	115,710	101,725	110,837	95,165

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (27,361)	$ (12,843)	$ (99,920)	$ (49,670)
Foreign currency translation adjustment	(4,077)	0	(4,139)	0
Change in unrealized (loss) gain on available-for-sale securities	(59)	(87)	678	42
Comprehensive loss	(31,497)	(12,930)	(103,381)	(49,628)
Comprehensive loss attributable to non-controlling interest	(54)	0	(179)	0
Comprehensive loss attributable to Sangamo Therapeutics, Inc.	$ (31,443)	$ (12,930)	$ (103,202)	$ (49,628)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Non- Controlling Interest
Beginning Balances (in shares) at Dec. 31, 2017		85,598
Beginning Balances at Dec. 31, 2017	$ 187,900	$ 856	$ 682,809	$ (495,479)	$ (286)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax (in shares)		1,922
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	13,696	$ 18	13,678
Issuance of common stock under employee stock purchase plan (in shares)		163
Issuance of common stock under employee stock purchase plan	690	$ 2	688
Issuance of common stock under public offering, net of issuance costs (in shares)		14,157
Issuance of common stock under public offering, net of issuance costs	215,757	$ 142	215,615
Stock-based compensation	10,374		10,374
Net unrealized gain (loss) on marketable securities	42				42
Net loss	(49,670)			(49,670)
Ending Balances (in shares) at Sep. 30, 2018		101,840
Ending Balances at Sep. 30, 2018	379,906	$ 1,018	923,164	(544,032)	(244)	0
Beginning Balances (in shares) at Jun. 30, 2018		101,624
Beginning Balances at Jun. 30, 2018	387,867	$ 1,016	918,197	(531,189)	(157)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax (in shares)		216
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	1,159	$ 2	1,157
Stock-based compensation	3,810		3,810
Net unrealized gain (loss) on marketable securities	(87)				(87)
Net loss	(12,843)			(12,843)		0
Ending Balances (in shares) at Sep. 30, 2018		101,840
Ending Balances at Sep. 30, 2018	379,906	$ 1,018	923,164	(544,032)	(244)	0
Beginning Balances (in shares) at Dec. 31, 2018		102,188
Beginning Balances at Dec. 31, 2018	367,257	$ 1,022	929,632	(562,696)	(1,440)	739
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax (in shares)		800
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	3,363	$ 8	3,355
Issuance of common stock under employee stock purchase plan (in shares)		132
Issuance of common stock under employee stock purchase plan	1,139	$ 1	1,138
Issuance of common stock under public offering, net of issuance costs (in shares)		12,650
Issuance of common stock under public offering, net of issuance costs	136,308	$ 127	136,181
Stock-based compensation	14,091		14,091
Acquisition of additional shares of Sangamo France/TxCell	(321)					(321)
Issuance costs related to Sangamo France/TxCell Acquisition	(25)		(25)
Foreign currency translation adjustment	(4,139)				(4,139)
Net unrealized gain (loss) on marketable securities	678				678
Net loss	(99,920)			(99,741)		(179)
Ending Balances (in shares) at Sep. 30, 2019		115,770
Ending Balances at Sep. 30, 2019	419,328	$ 1,158	1,084,372	(661,540)	(4,901)	239
Beginning Balances (in shares) at Jun. 30, 2019		115,603
Beginning Balances at Jun. 30, 2019	445,748	$ 1,156	1,078,976	(634,233)	(765)	614
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax (in shares)		167
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, net of tax	704	$ 2	702
Stock-based compensation	4,701		4,701
Acquisition of additional shares of Sangamo France/TxCell	(321)					(321)
Issuance costs related to Sangamo France/TxCell Acquisition	(7)		(7)
Foreign currency translation adjustment	(4,077)				(4,077)
Net unrealized gain (loss) on marketable securities	(59)				(59)
Net loss	(27,361)			(27,307)		(54)
Ending Balances (in shares) at Sep. 30, 2019		115,770
Ending Balances at Sep. 30, 2019	$ 419,328	$ 1,158	$ 1,084,372	$ (661,540)	$ (4,901)	$ 239

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities:
Net loss	$ (99,920)	$ (49,670)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	2,742	1,668
Amortization of discount on marketable securities	(3,715)	(4,043)
Gain on free shares	(488)	0
Stock-based compensation	14,091	10,374
Net loss on lease termination	218	0
Other	(29)	715
Net changes in operating assets and liabilities:
Interest receivable	(305)	(443)
Accounts receivable	(17,280)	(2,225)
Prepaid expenses and other assets	(4,734)	(1,851)
Operating lease right-of-use assets	3,796	0
Accounts payable and accrued liabilities	(1,753)	789
Accrued compensation and employee benefits	1,608	1,127
Deferred revenues	(20,477)	118,540
Long-term portion of lease liabilities	(920)	0
Other non-current liabilities	3,580	1,730
Net cash (used in) provided by operating activities	(123,586)	76,711
Investing Activities:
Purchases of marketable securities	(321,390)	(451,239)
Maturities of marketable securities	292,147	230,547
Purchases of property and equipment	(13,894)	(15,028)
Purchase of additional Sangamo France shares	(262)	0
Other investment	0	(5,221)
Net cash used in investing activities	(43,399)	(240,941)
Financing Activities:
Proceeds from public offering of common stock, net of issuance costs	136,308	215,757
Taxes paid related to net share settlement of equity awards	(388)	(83)
Proceeds from issuance of common stock	4,890	14,469
Net cash provided by financing activities	140,810	230,143
Effects of changes in foreign exchange rates	48	0
Net (decrease) increase in cash, cash equivalents, and restricted cash	(26,127)	65,913
Cash, cash equivalents, and restricted cash, beginning of period	143,918	53,326
Cash, cash equivalents, and restricted cash, end of period	117,791	119,239
Supplemental disclosure of non-cash activities:
Property and equipment included in unpaid liabilities	4,257	5,813
Right-of-use assets obtained in exchange for lease obligations	$ 29,647	$ 0

Organization, Basis of Presenta

Organization, Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Organization, Basis of Presentation and Summary of Significant Accounting Policies	ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Overview Sangamo Therapeutics, Inc. (“Sangamo” or the “Company”) was incorporated in the State of Delaware in June 1995 and changed its name from Sangamo Biosciences, Inc. in January 2017. Sangamo is focused on the research, development and commercialization of novel therapeutic strategies for unmet medical needs. Sangamo’s genome editing and gene regulation technology platform is enabled by the engineering of a class of transcription factors known as zinc finger DNA-binding proteins (“ZFPs”). Potential applications of Sangamo’s technology include development of human therapeutics, plant agriculture and enhancement of pharmaceutical protein production. Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) for interim financial information and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included. Operating results for the three and nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 . The Condensed Consolidated Balance Sheet data at December 31, 2018 was derived from the audited consolidated financial statements included in Sangamo’s Annual Report on Form 10-K for the year ended December 31, 2018 (the “ 2018 Annual Report”) as filed with the SEC on March 1, 2019. The accompanying Condensed Consolidated Financial Statements and related financial information should be read in conjunction with the audited financial statements and footnotes thereto for the year ended December 31, 2018 , included in the 2018 Annual Report. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and the accompanying notes. On an ongoing basis, management evaluates its estimates including critical accounting policies or estimates related to revenue recognition, clinical trial accruals, fair value of assets and liabilities, including from acquisitions, and stock-based compensation. Estimates are based on historical experience and on various other market specific and other relevant assumptions that the Company believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. In March 2019, the Company recorded an adjustment to revenue related to a change in estimate in connection with the hemophilia A collaboration agreement with Pfizer Inc. (“Pfizer”). This adjustment was a direct result of the increase in project scope during the first quarter of 2019 and the corresponding costs which resulted in a decrease in the measure of proportional performance. This adjustment decreased revenue by $3.0 million , increased net loss by $3.0 million and increased the Company’s basic net loss per share by $0.03 for the nine months ended September 30, 2019 . Foreign Currency Translation The functional currency of the Company’s foreign subsidiaries is primarily the Euro. Assets and liabilities denominated in foreign currencies are translated to U.S. dollars using the exchange rates at the balance sheet date. Foreign currency translation adjustments are recorded as a component of Accumulated Other Comprehensive Income (Loss) (“AOCI”) within stockholders’ equity. Revenues and expenses from the Company’s foreign subsidiaries are translated using the monthly average exchange rates in effect during the period in which the transactions occur. Foreign currency transaction gains and losses are recorded in interest and other income, net, on the Company’s Condensed Consolidated Statements of Operations. Reclassifications Certain prior period amounts in the accompanying Condensed Consolidated Financial Statements have been reclassified to conform to the current period presentation. These reclassifications had no effect on the reported results of operations. The Company reclassified $0.6 million from Intangible assets to Other non-current assets on the Condensed Consolidated Balance Sheet as of December 31, 2018 . Cash and Cash Equivalents Sangamo considers all highly-liquid investments purchased with original maturities of three months or less at the purchase date to be cash equivalents. Cash and cash equivalents consist of cash, deposits in demand money market accounts and commercial paper. Marketable Securities Sangamo classifies its marketable securities as available-for-sale and records its investments at estimated fair value based on quoted market prices or observable market inputs of almost identical assets, with the unrealized holding gains and losses included in AOCI. The Company’s investments are subject to a periodic impairment review. The Company recognizes an impairment charge, if material; when a decline in the fair value of its investments below the cost basis is judged to be other-than-temporary. The Company considers various factors in determining whether to recognize an impairment charge, including the length of time and extent to which the fair value has been less than the Company’s cost basis, the financial condition and near-term prospects of the investee and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in the market value. Realized gains and losses on available-for-sale securities are included in other income, net, which are determined using the specific identification method. Going Concern Sangamo is currently working on a number of long-term development projects that will involve experimental technology. The projects may require several years and substantial expenditures to complete and ultimately may be unsuccessful. The Company plans to finance operations with available cash resources, collaborations and strategic partnerships funds, research grants and from the issuance of equity or debt securities. Sangamo believes that its available cash, cash equivalents and investments as of September 30, 2019 , and expected revenues from collaborations, strategic partnerships and research grants, will be adequate to fund its operations at least through the next twelve months from the date the financial statements are issued. Sangamo will require additional financial resources to complete the development and commercialization of its products including ZFP therapeutic products. Additional capital may not be available on terms acceptable to the Company, or at all. If adequate funds are not available, or if the terms of potential funding sources are unfavorable, the Company’s business and ability to develop its technology and ZFP therapeutic products would be harmed. Furthermore, any sales of additional equity securities may result in dilution to the Company’s stockholders, and any debt financing may include covenants that restrict the Company’s business. Concentrations of Risk Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to a concentration of credit risk to the extent of the fair value recorded in the Condensed Consolidated Balance Sheets. The Company invests cash that is not required for immediate operating needs primarily in highly liquid instruments that bear minimal risk. The Company has established guidelines relating to the quality, diversification, and maturities of securities to enable the Company to manage its credit risk. The Company is exposed to credit risk in the event of a default by the financial institutions holding its cash, cash equivalents and investments and issuers of investments to the extent recorded on the Condensed Consolidated Balance Sheets. Certain materials and key components that the Company utilizes in its operations are obtained through single suppliers. Since the suppliers of key components and materials must be named in an investigational new drug application filed with the U.S. Food and Drug Administration for a product, significant delays can occur if the qualification of a new supplier is required. If delivery of material from the Company’s suppliers were interrupted for any reason, the Company may be unable to supply any of its product candidates for clinical trials. Fair Value Measurements The carrying amounts for financial instruments consisting of cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate fair value due to their short maturities. Marketable securities are stated at their estimated fair values. The free share asset/liability is measured using a binomial-lattice pricing model and is reviewed each reporting period and adjusted, as needed and is expected to approximate fair value. Leases The Company determines if an arrangement is or contains a lease at inception by assessing whether the arrangement contains an identified asset and whether it has the right to control the identified asset. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Lease liabilities are recognized at the lease commencement date based on the present value of future lease payments over the lease term. ROU assets are based on the measurement of the lease liability and also include any lease payments made prior to or on lease commencement and exclude lease incentives and initial direct costs incurred, as applicable. As the implicit rate in the Company’s leases is generally unknown, the Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of remaining lease payments. The incremental borrowing rate represents an estimate of the interest rate the Company would incur at lease commencement to borrow an amount equal to the lease payments on a collateralized basis over the term of a lease in a similar economic environment. The Company gives consideration to its credit risk, term of the lease, total lease payments and adjusts for the impacts of collateral, as necessary, when calculating its incremental borrowing rates. The lease terms may include options to extend or terminate the lease when it is reasonably certain the Company will exercise any such options. Rent expense for the Company’s operating leases is recognized on a straight-line basis over the lease term. The Company has elected to not separate lease and non-lease components for its real estate and copier leases and, as a result, accounts for any lease and non-lease components as a single lease component. The Company has also elected to not apply the recognition requirement to any leases with a term of 12 months or less and does not include an option to purchase the underlying asset that the Company is reasonably certain to exercise. Revenue Recognition Effective January 1, 2018, the Company adopted the provisions of Accounting Standards Codification (“ASC”) Topic 606 - Revenue from Contracts with Customers (“ASC Topic 606”) using the modified retrospective method, resulting in a change to its accounting policy for revenue recognition. ASC Topic 606 establishes a unified model to determine how revenue is recognized. The Company’s contract revenues consist of strategic partnering collaboration agreements and research activity grants and licensing. Research and licensing agreements typically include upfront signing or license fees, cost reimbursements, research services, minimum sublicense fees, milestone payments and royalties on future licensee’s product sales. The Company has both fixed and variable consideration. Non-refundable upfront fees and funding of research and development activities are considered fixed, while milestone payments are identified as variable consideration. Sangamo’s research grants are typically multi-year agreements and provide for the reimbursement of qualified expenses for research and development as defined under the terms of the grant agreement. Revenues under research grant agreements are recognized when the related qualified research expenses are incurred. Deferred revenue represents the portion of research or license payments received and incurred but not earned. In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account in ASC Topic 606. The Company’s performance obligations include license rights, development services and services associated with regulatory submission and approval processes. Revenues from research services are made under strategic partnering agreements and collaborations are generally recognized as the services are provided while revenues from non-refundable upfront fees are recognized over time either by measuring progress towards satisfaction of the relevant performance obligation, using input method or on a straight-line basis when a performance obligation is assumed to be satisfied evenly over a period of time (or when the entity has a stand-ready obligation). Significant management judgment is required to determine the level of effort required under an arrangement and the period over which the Company expects to complete its performance obligations under the arrangement which may include reimbursement rates for personnel costs, external reimbursable costs, estimated period of performance and estimating the progress towards the satisfaction of performance obligation. If the Company cannot reasonably estimate when its performance obligations either are completed or become inconsequential, then revenue recognition is deferred until the Company can reasonably make such estimates. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint and, if necessary, adjusts its estimate of the overall transaction price. Revenue is then recognized over the remaining estimated period of performance using the cumulative catch-up method. The estimated period of performance and project costs, such as personnel and manufacturing cost, are reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables. As part of the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the stand-alone selling price of each performance obligation identified in the contract. The Company uses key assumptions to determine the stand-alone selling price which may include forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success. Related costs and expenses under these arrangements have historically approximated the revenues recognized. For the nine months ended September 30, 2019 , revenues related to Kite Pharma, Inc. (“Kite”), a wholly-owned subsidiary of Gilead Sciences, Inc., Bioverativ Inc., (now Sanofi Genzyme, a global business unit of Sanofi S.A. (“Sanofi”)), and the Company's hemophilia A collaboration agreement with Pfizer represented 55% , 29% and 11% , respectively, of the Company’s total revenue. For the three months ended September 30, 2019 , revenues related to Kite, Sanofi and the Company's hemophilia A collaboration agreement with Pfizer represented 40% , 40% and 16% , respectively, of the Company’s total revenue. During the nine months ended September 30, 2018 , revenues related to the Company's hemophilia A collaboration agreement with Pfizer, Kite and Sanofi represented 46% , 29% and 19% respectively, of the Company’s total revenue. For the three months ended September 30, 2018 , revenues related to the Company's hemophilia A collaboration agreement with Pfizer, Kite and Sanofi represented 44% , 38% and 10% , respectively, of the Company’s total revenue. Receivables from collaborations are typically unsecured and are concentrated in the biopharmaceutical industry. Accordingly, the Company may be exposed to credit risk generally associated with biopharmaceutical companies or specific to its collaboration agreements. To date, the Company has not experienced any losses related to these receivables. Funds received from third parties under contract or grant arrangements are recorded as revenue if the Company is deemed to be the principal participant in the arrangements because the activities under the contracts or grants are part of the Company’s development programs. Contract funds received are not refundable and are recognized when the related qualified research and development costs are incurred and there is reasonable assurance that the funds will be received. Funds received in advance are recorded as deferred revenue. Recent Accounting Pronouncements Recently Adopted Simplified Disclosure In August 2018, the SEC adopted amendments to certain disclosure requirements in Securities Act Release No. 33-10532, Disclosure Update and Simplification , as updated. These amendments eliminate, modify, or integrate into other SEC requirements certain disclosure rules. Among the amendments is the requirement to present an analysis of changes in stockholders’ equity in the interim financial statements included in quarterly reports on Form 10-Q. The analysis, which can be presented as a footnote or separate statement, is required for the current and comparative quarter and year-to-date interim periods. The amendments are effective for all filings made on or after November 5, 2018. As such, the Company adopted these SEC amendments on November 5, 2018 and has presented the analysis of changes in stockholders’ equity in these interim financial statements for September 30, 2019 and 2018 presented in this Quarterly Report on Form 10-Q. The Company’s adoption of these SEC amendments had no material effect on the Company’s reporting of financial position, results of operations, cash flows or stockholders’ equity. Accounting for Leases In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016 -2 , Leases (“ASC Topic 842”). ASC Topic 842 amends a number of aspects of lease accounting, including requiring lessees to recognize almost all leases with a term greater than one year as a ROU asset and corresponding liability, measured at the present value of the lease payments. On January 1, 2019, the Company adopted ASC Topic 842 using the modified retrospective approach with a cumulative-effect adjustment of $0.9 million reflected as a decrease to the opening balance of accumulated deficit as of the adoption date. Results for the three and nine months ended September 30, 2019 are presented under ASC Topic 842. No prior period amounts were adjusted and continue to be reported in accordance with previous lease guidance, ASC Topic 840 — Leases (“ASC Topic 840”). ASC Topic 842 provides a number of optional practical expedients in transition. The Company elected the practical expedients to not reassess its prior conclusions about lease identification under the new standard, to not reassess lease classification, and to not reassess initial direct costs. The Company did not elect the practical expedient allowing the use-of-hindsight which would require the Company to reassess the lease term of its leases based on all facts and circumstances through the effective date and did not elect the practical expedient pertaining to land easements as this is not applicable to the current contract portfolio. The impact of the adoption of ASC Topic 842 on the accompanying Condensed Consolidated Balance Sheet as of January 1, 2019 was as follows (in thousands): December 31, 2018 Adjustments Due to the Adoption of ASC Topic 842 January 1, 2019 Assets: Property and equipment, net $ 78,723 $ (62,500 ) $ 16,223 Operating lease right-of-use assets — 8,753 8,753 Prepaid rent — 36,025 36,025 Liabilities: Operating lease liabilities - current (1) — 1,408 1,408 Deferred rent (1) 271 (271 ) — Build-to-suit lease obligation (2) 27,689 (27,689 ) — Operating lease liabilities - long-term (2) — 7,933 7,933 Accumulated deficit (562,696 ) 897 (561,799 ) ___________________ (1) Operating lease liabilities – current and deferred rent are included in accounts payable and accrued liabilities on the Condensed Consolidated Balance Sheets. (2) Build-to-suit lease obligation and operating lease liabilities – long-term are included in long-term portion of lease liabilities on the Condensed Consolidated Balance Sheets. The adjustments due to the adoption of ASC Topic 842 primarily related to the recognition of operating lease ROU assets and operating lease liabilities for the Company’s leases. In addition, the adoption of ASC Topic 842 resulted in a change in accounting of the build-to-suit component of two leases under ASC Topic 840 to operating leases under ASC Topic 842 and as a result the Company derecognized the estimated fair value of the building shells that were included in Property and equipment, net as of December 31, 2018 , as the Company had been deemed to own these buildings under ASC Topic 840. For additional discussion of the build-to-suit properties, see “Note 7 – Property and equipment, net ” to the Company’s consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2018 filed with the SEC on March 1, 2019. For a description of the leases, see “Note 7 – Commitments and Contingencies – Leases ” in these Condensed Consolidated Financial Statements. Not yet adopted Collaborative Arrangements In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (ASC Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 (“ASC Topic 808”), which clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC Topic 606 when the counterparty is a customer. In addition, ASC Topic 808 precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. This guidance will be effective for the Company beginning January 1, 2020. The Company is currently evaluating the impact of the adoption of this standard on its consolidated financial statements. Goodwill Impairment Testing In January 2017, the FASB issued ASU No. 2017 -4 , Intangibles – Goodwill and Other (Topic 350): Simplifying the Test of Goodwill Impairment (“ASU 2017 -4 ”). The new guidance simplifies the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. ASU 2017 -4 requires goodwill impairment to be measured as the amount by which a reporting unit’s carrying amount exceeds its fair value, not to exceed the carrying amount of its goodwill. ASU 2017 -4 requires prospective application and is effective for annual periods beginning after December 15, 2019. ASU 2017 -4 will require the Company to amend its methodology for determining any goodwill impairment beginning in 2020.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The Company measures certain financial assets and liabilities at fair value on a recurring basis, including cash equivalents, available-for-sale marketable securities and the free share asset/liability. Fair value is determined based on a three-tier hierarchy under the authoritative guidance for fair value measurements and disclosures that prioritizes the inputs used in measuring fair value as follows: Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2: Quoted prices in markets that are not active or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability; and Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). The fair value measurements of the Company’s cash equivalents, available-for-sale marketable securities and the free share asset/liability are identified at the following levels within the fair value hierarchy (in thousands): September 30, 2019 Total Level 1 Level 2 Level 3 Assets: Cash equivalents: Money market funds $ 77,213 $ 77,213 $ — $ — Total 77,213 77,213 — — Marketable securities: Commercial paper securities 180,812 — 180,812 — Corporate debt securities 71,114 — 71,114 — U.S. government-sponsored entity debt securities 41,424 — 41,424 — Total 293,350 — 293,350 — Total cash equivalents and marketable securities $ 370,563 $ 77,213 $ 293,350 $ — Free shares asset $ 239 $ — $ — $ 239 December 31, 2018 Total Level 1 Level 2 Level 3 Assets: Cash equivalents: Money market funds $ 103,291 $ 103,291 $ — $ — Total 103,291 103,291 — — Marketable securities: Commercial paper securities 177,224 — 177,224 — Corporate debt securities 63,870 — 63,870 — U.S. government-sponsored entity debt securities 18,621 — 18,621 — Total 259,715 — 259,715 — Total cash equivalents and marketable securities $ 363,006 $ 103,291 $ 259,715 $ — Liabilities: Free shares liability $ 154 $ — $ — $ 154 Cash Equivalents and Marketable Securities The Company generally classifies its marketable securities as Level 2. Instruments are classified as Level 2 when observable market prices for identical securities that are traded in less active markets are used. When observable market prices for identical securities are not available, such instruments are priced using benchmark curves, benchmarking of like securities, sector groupings, matrix pricing and valuation models. These valuation models are proprietary to the pricing providers or brokers and incorporate a number of inputs, including, listed in approximate order of priority: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data including market research publications. For certain security types, additional inputs may be used, or some of the standard inputs may not be applicable. Evaluators may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs listed are available for use in the evaluation process for each security evaluation on any given day. Free Share Asset/Liability As a result of the July 20, 2018 Share Purchase Agreement (“SPA”) to acquire TxCell S.A. (“TxCell” or "Sangamo France") (see Note 10 — Acquisition of Sangamo Therapeutics France S.A.S. ), the Company entered into arrangements with the holders of approximately 477,000 “free shares” of TxCell pursuant to which the Company has the right to purchase such shares from the holders thereof (a call option) and such holders have the right to sell to the Company such shares from time to time through mid-2021 (a put option). The Company initially recorded a liability of $0.2 million on the acquisition date. The put options were classified within Level 3 of the fair value hierarchy as the Company utilized a binomial-lattice pricing model (the “Monte Carlo simulation model”) that involved certain market conditions to estimate the fair value of the options. The assumptions used in this simulation model are reviewed on a quarterly basis and adjusted, as needed. Subsequent changes in the fair value of the free shares are recorded in general and administrative expenses in the Condensed Consolidated Statements of Operations. During the three months ended September 30, 2019, the Company purchased approximately 111,000 shares of the 477,000 total free shares for a cash payment of approximately $0.3 million upon exercise of the put options. As of September 30, 2019, approximately 366,000 free shares remain outstanding and subject to purchase by the Company. The free shares liability was approximately $0.2 million at December 31, 2018 and the Company recognized a gain due to an increase in the fair value of the free shares of approximately $0.5 million for the nine months ended September 30, 2019 , offset by approximately $0.1 million for the shares purchased in September 2019, bringing the balance to an asset of approximately $0.2 million at September 30, 2019 . Free Shares valuation assumptions: September 30, December 31, 2018 Sangamo Stock Price (USD) $ 9.05 $ 11.48 TxCell Stock Price (EUR) € 2.23 € 2.58 EUR / USD Exchange Rate 0.91 0.87 Estimated Correlation Sangamo and TxCell Stock Prices 100.0% — Sangamo Stock Price (USD) Volatility Estimate 75.0% 79.9% TxCell Stock Price (EUR) Volatility Estimate 75.0% 8.6% EUR / USD Exchange Rate Volatility Estimate 6.8% 7.7% Risk Free Rate and Cost of Debt by Expected Exercise Date Varies Varies

Cash and Marketable Securities

Cash and Marketable Securities	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Cash and Marketable Securities	CASH AND MARKETABLE SECURITIES Cash, Cash Equivalents and Restricted Cash A reconciliation of cash, cash equivalents and restricted cash reported within the Condensed Consolidated Balance Sheets to the amounts reported within the accompanying Condensed Consolidated Statements of Cash Flows was as follows (in thousands): September 30, December 31, September 30, December 31, Cash and cash equivalents $ 114,291 $ 140,418 $ 39,298 $ 49,826 Restricted cash included in Restricted cash, current portion 2,000 — — — Restricted cash included in Non-current restricted cash 1,500 3,500 79,941 3,500 Cash, cash equivalents and restricted cash as reported within the accompanying Condensed Consolidated Statements of Cash Flows $ 117,791 $ 143,918 $ 119,239 $ 53,326 Restricted cash consists of a letter of credit for $3.5 million as a deposit for the Brisbane lease, of which $2.0 million was released in October 2019. Cash Equivalents and Available-for-sale Securities The table below summarizes the Company’s cash equivalents and available-for-sale securities (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Estimated Fair Value September 30, 2019 Assets Cash equivalents: Money market funds $ 77,213 $ — $ — $ 77,213 Total 77,213 — — 77,213 Available-for-sale securities: Commercial paper securities 180,590 224 (2 ) 180,812 Corporate debt securities 70,947 167 — 71,114 U.S. government-sponsored entity debt securities 41,394 30 — 41,424 Total 292,931 421 (2 ) 293,350 Total cash equivalents and available-for-sale securities $ 370,144 $ 421 $ (2 ) $ 370,563 December 31, 2018 Assets Cash equivalents: Money market funds $ 103,291 $ — $ — $ 103,291 Total 103,291 — — 103,291 Available-for-sale securities: Commercial paper securities 177,353 — (129 ) 177,224 Corporate debt securities 63,981 — (111 ) 63,870 U.S. government-sponsored entity debt securities 18,640 — (19 ) 18,621 Total 259,974 — (259 ) 259,715 Total cash equivalents and available-for-sale securities $ 363,265 $ — $ (259 ) $ 363,006 The fair value of investments available-for-sale by contractual maturity were as follows (in thousands): September 30, December 31, Maturing in one year or less $ 240,561 $ 259,715 Maturing after one year through five years 52,789 — Total $ 293,350 $ 259,715 The Company had no material realized losses of its available-for-sale securities for the three and nine months ended September 30, 2019 or 2018 . Sangamo has the intent and ability to hold its investments for a period of time sufficient to allow for any anticipated recovery in market value. No investments were other-than-temporarily impaired at either September 30, 2019 or December 31, 2018 .

Basic and Diluted Net Loss Per

Basic and Diluted Net Loss Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Basic and Diluted Net Loss Per Share	BASIC AND DILUTED NET LOSS PER SHARE Basic net loss per share attributable to Sangamo Therapeutics, Inc. stockholders has been computed by dividing net loss attributable to Sangamo Therapeutics, Inc. stockholders by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders is calculated by dividing net loss attributable to Sangamo Therapeutics, Inc. stockholders by the weighted-average number of shares of common stock and potential dilutive securities outstanding during the period. The total number of shares subject to stock options and restricted stock units (“RSUs”) outstanding and the employee stock purchase plan (“ESPP”) shares reserved for issuance, which are all anti-dilutive, were excluded from consideration in the calculation of diluted net loss per share attributable to Sangamo Therapeutics, Inc. stockholders. Stock options and RSUs outstanding and ESPP shares reserved for issuance as of September 30, 2019 and 2018 totaled 10,370,481 and 8,770,775 , respectively.

Major Customers, Partnerships a

Major Customers, Partnerships and Strategic Alliances	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Major Customers, Partnerships and Strategic Alliances	MAJOR CUSTOMERS, PARTNERSHIPS AND STRATEGIC ALLIANCES Kite Pharma, Inc. In February 2018, the Company entered into a global collaboration and license agreement with Kite, which it amended and restated in September 2019, for the research, development and commercialization of potential engineered cell therapies for cancer. In this collaboration, Sangamo is working together with Kite on a research program under which the companies are designing ZFNs and viral vectors to disrupt and insert certain genes in T-cells and natural killer cells (“NK-cells”) including the insertion of genes that encode chimeric antigen receptors, T-cell receptors, and NK-cell receptors directed to mutually agreed targets. Kite is responsible for all clinical development and commercialization of any resulting products and has announced that they expect to initiate a clinical trial evaluating KITE-037, an allogeneic anti-CD19 CAR-T cell therapy, in 2020. The Kite agreement became effective on April 5, 2018 . Subject to the terms of this agreement, the Company granted Kite an exclusive, royalty-bearing, worldwide sublicensable license under the Company’s relevant patents and know-how to develop, manufacture and commercialize, for the purpose of treating cancer, specific cell therapy products that may result from the research program and that are engineered ex vivo using selected zinc finger nucleases (“ZFNs”) and viral vectors developed under the research program to express chimeric antigen receptors (“CARs”), T-cell receptors (“TCRs”) or NK-cell receptors (“NKRs”) directed to candidate targets. During the research program term and subject to certain exceptions except pursuant to this agreement, the Company is prohibited from researching, developing, manufacturing and commercializing, for the purpose of treating cancer, any cell therapy product that, as a result of ex vivo genome editing, expresses a CAR, TCR or NKR that is directed to a target expressed on or in a human cancer cell. After the research program term concludes and subject to certain exceptions, except pursuant to this agreement, the Company will be prohibited from developing, manufacturing and commercializing, for the purpose of treating cancer, any cell therapy product that, as a result of ex vivo genome editing, expresses a CAR, TCR or NKR that is directed to a candidate target. Following the effective date, in April 2018, the Company received a $150.0 million upfront payment from Kite. In addition, Kite will reimburse the Company’s direct costs to conduct the joint research program, and Kite will be responsible for all subsequent development, manufacturing and commercialization of any licensed products. Sangamo is also eligible to receive contingent development- and sales-based milestone payments that could total up to $3.01 billion if all of the specified milestones set forth in this agreement are achieved. Of this amount, approximately $1.26 billion relates to the achievement of specified research, clinical development, regulatory and first commercial sale milestones, and approximately $1.75 billion relates to the achievement of specified sales-based milestones if annual worldwide net sales of licensed products reach specified levels. Each development- and sales-based milestone payment is payable (i) only once for each licensed product regardless of the number of times that the associated milestone event is achieved by such licensed product, and (ii) only for the first ten times that the associated milestone event is achieved regardless of the number of licensed products that may achieve such milestone event. In addition, the Company will be entitled to receive escalating, tiered royalty payments with a percentage in the single digits based on potential future annual worldwide net sales of licensed products. These royalty payments will be subject to reduction due to patent expiration, entry of biosimilar products to the market and payments made under certain licenses for third-party intellectual property. The initial research term in the agreement is six years . Kite has an option to extend the research term of the agreement for up to two additional one-year periods for a separate upfront fee of $10.0 million per year. All contingent payments under the agreement, when earned, will be non-refundable and non-creditable. In connection with the amendment and restatement of the agreement in September 2019, the Company entered into a new research plan with Kite, with estimated reimbursable service cost of approximately $3.4 million . The Company concluded the total transaction price under this agreement is $189.3 million and includes the upfront license fee of $150.0 million and $39.3 million estimated reimbursable service costs for identified research projects over the estimated performance period. Further, the Company concluded the estimated fees for the presumed exercise of the research term extension options and all milestone amounts are fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including the fact that achievement of the milestones at this time is uncertain and contingent upon future events which are uncertain at this time. The Company will re-evaluate the transaction price including the estimated variable consideration included in the transaction price and all constrained amounts in each reporting period and as uncertain events are resolved or other changes in circumstances occur. None of the development and sales-based milestone payments have been included in the transaction price. Kite has the right to terminate this agreement in its entirety or on a per licensed product or per candidate target basis for any reason after a specified notice period. Each party has the right to terminate this agreement on account of the other party’s bankruptcy or material, uncured breach. The Company has identified the primary performance obligations within the Kite agreement as: (1) a license to the technology along with the stand by ready obligation to perform research services, and (2) the on-going research services. Revenue from the upfront license fee relates to access to the license and Company’s obligation to stand-ready to perform such research services as additional targets are selected by Kite. As a result of this obligation to perform research services when and if requested throughout the duration of the contract, the fee for the license and the stand-ready obligation will be recognized over time on a straight-line basis through June 2024, the estimated period of the stand-ready obligation. Revenue from the reimbursable costs related to the integrated service deliverable is recognized as the research services are performed. The estimated period of performance and project cost is reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables. As of September 30, 2019 and December 31, 2018 , the Company had deferred revenue of $112.8 million and $131.5 million , respectively, related to this agreement. Revenues recognized under the agreement for the three and nine months ended September 30, 2019 and 2018 were as follows (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Revenue related to Kite agreement: Recognition of license and stand-ready fee $ 6,296 $ 6,296 $ 18,682 $ 12,249 Research services 2,565 2,732 7,551 4,295 Total $ 8,861 $ 9,028 $ 26,233 $ 16,544 Pfizer Inc. SB -525 Global Collaboration and License Agreement In May 2017, the Company entered into an exclusive global collaboration and license agreement with Pfizer, pursuant to which it established a collaboration for the research, development and commercialization of SB-525, its gene therapy product candidate for hemophilia A, and closely related products. Under this agreement, the Company is responsible for conducting the Phase 1/2 clinical trial and for certain manufacturing activities for SB-525, while Pfizer is responsible for subsequent worldwide development, manufacturing, marketing and commercialization of SB-525. Sangamo may also collaborate in the research and development of additional AAV-based gene therapy products for hemophilia A. The Company originally received an upfront fee of $70.0 million and is eligible to receive development milestone payments contingent on the achievement of specified clinical development, intellectual property, regulatory and first commercial sale milestones for SB-525 and potentially other products. In addition, Sangamo is eligible to receive up to $208.5 million in payments upon the achievement of specified clinical development, intellectual property and regulatory milestones and up to $266.5 million in payments upon first commercial sale milestones for SB-525 and potentially other products. The total amount of potential clinical development, intellectual property, regulatory and first commercial sale milestone payments, assuming the achievement of all specified milestones in the hemophilia A Pfizer agreement, is up to $475.0 million , which includes up to $300.0 million for SB-525 and up to $175.0 million for other products that may be developed under the agreement, subject to reduction on account of payments made under certain licenses for third-party intellectual property. In addition, Pfizer agreed to pay the Company royalties for each potential licensed product developed under the agreement that are an escalating tiered, double-digit percentage of the annual net sales of such product and are subject to reduction due to patent expiration, entry of biosimilar products to the market and payment made under certain licenses for third-party intellectual property. To date, no milestone payments have been received and no products have been approved and therefore no royalty fees have been earned under the hemophilia A Pfizer agreement. The Company concluded the total transaction price under this agreement is $70.0 million , which represents the upfront fee received. Sangamo is responsible for internal and external research costs as part of the upfront fee and has the ability to request additional reimbursement from Pfizer if certain conditions are met. None of the clinical or regulatory milestones have been included in the transaction price, as all milestone amounts are fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including the fact that achievement of the milestones at this time is uncertain and contingent upon future periods when the uncertainty related to the variable consideration is resolved. The Company will re-evaluate the transaction price, including its estimated variable consideration included in the transaction price and all constrained amounts in each reporting period and as uncertain events are resolved or other changes in circumstances occur. Subject to the terms of the agreement, the Company granted Pfizer an exclusive worldwide royalty-bearing license, with the right to grant sublicenses, to use certain technology controlled by the Company for the purpose of developing, manufacturing and commercializing SB-525 and related products. Pfizer granted the Company a non-exclusive, worldwide, royalty free, fully paid license, with the right to grant sublicenses, to use certain manufacturing technology developed under the agreement and controlled by Pfizer to manufacture the Company’s products that utilize the AAV delivery system. During a specified period, neither the Company nor Pfizer will be permitted to clinically develop or commercialize, outside of the collaboration, certain AAV-based gene therapy products for hemophilia A. Unless earlier terminated, the agreement has a term that continues on a per product and per country basis until the later of (i) the expiration of patent claims that cover the product in a country, (ii) the expiration of regulatory exclusivity for a product in a country, and (iii) fifteen years after the first commercial sale of a product in a country. Pfizer has the right to terminate the agreement without cause in its entirety or on a per product or per country basis. The agreement may also be terminated by either party based on an uncured material breach by the other party or the bankruptcy of the other party. Upon termination for any reason, the license granted by the Company to Pfizer to develop, manufacture and commercialize SB-525 and related products will automatically terminate. Upon termination by the Company for cause or by Pfizer in any country or countries, Pfizer will automatically grant the Company an exclusive, royalty-bearing license under certain technology controlled by Pfizer to develop, manufacture and commercialize SB-525 in the terminated country or countries. The Company has identified the performance obligations within the hemophilia A Pfizer agreement as a license to the technology and on-going research services. The Company concluded that the license is not discrete as it does not have stand-alone value to Pfizer apart from the research services to be performed by the Company pursuant to the agreement. As a result, the Company recognizes revenue from the upfront payment based on proportional performance of the on-going services through 2020, the estimated period the Company will perform research services. The estimation of progress towards the satisfaction of its performance obligation and project cost is reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables. As of September 30, 2019 and December 31, 2018 , the Company had deferred revenue of $12.4 million and $10.0 million , respectively, related to this agreement. Revenues recognized under the agreement for the three and nine months ended September 30, 2019 and 2018 were as follows (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Recognition of upfront fee related to Pfizer SB-525 agreement $ 3,440 $ 10,421 $ 5,035 $ 26,262 In the first quarter of 2019, the Company updated its estimated project cost and related revenues under this program. This adjustment was a direct result of the increase in project scope during the first quarter of 2019 and the corresponding costs which resulted in a decrease in the measure of proportional performance. During the nine months ended September 30, 2019 , the Company recognized $5.0 million in revenues related to the Pfizer SB-525 agreement which were net of the approximately $3.0 million reduction in revenues recorded in the three months ended March 31, 2019 related to the updated estimated project cost. C 9 ORF 72 Research Collaboration and License Agreement In December 2017 , the Company entered into a separate exclusive, global collaboration and license agreement with Pfizer for the development and commercialization of potential gene therapy products that use ZFP transcription factors (“TFs”) to treat amyotrophic lateral sclerosis (“ALS”) and frontotemporal lobar degeneration (“FTLD”) linked to mutations of the C 9 ORF 72 gene. Pursuant to this agreement, the Company agreed to work with Pfizer on a research program to identify, characterize and preclinically develop ZFP TFs that bind to and specifically reduce expression of the mutant form of the C 9 ORF 72 gene. The Company received a $12.0 million upfront payment from Pfizer and is eligible to receive up to $60.0 million in development milestone payments from Pfizer contingent on the achievement of specified preclinical development, clinical development and first commercial sale milestones, and up to $90.0 million commercial milestone payments if annual worldwide net sales of the licensed products reach specified levels. In addition, Pfizer will pay the Company royalties based on an escalating tiered, mid- to high-single digit percentage of the annual worldwide net sales of the licensed products. These royalty payments are subject to reduction due to patent expiration, entry of biosimilar products to the market and payments made under certain licenses for third party intellectual property. Each party will be responsible for the cost of its performance of the research program. Pfizer will be operationally and financially responsible for subsequent development, manufacturing and commercialization of the licensed products. The Company concluded the total transaction price under this agreement is $12.0 million , which represents the upfront fee. None of the clinical or regulatory milestones have been included in the transaction price, as all milestone amounts are fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including the fact that achievement of the milestones at this time is uncertain and contingent upon future periods when the uncertainty related to the variable consideration is resolved. The Company will re-evaluate the transaction price, including its estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. Subject to the terms of this agreement, the Company granted Pfizer an exclusive, royalty-bearing, worldwide license under the Company’s relevant patents and know‑how to develop, manufacture and commercialize gene therapy products that use resulting ZFP TFs that satisfy pre‑agreed criteria. During a specified period, neither the Company nor Pfizer will be permitted to research, develop, manufacture or commercialize outside of the collaboration any ZFPs that specifically bind to the C9ORF72 gene. Unless earlier terminated, the agreement has a term that continues on a per licensed product and per country basis until the later of (i) the expiration of patent claims that cover the licensed product in a country, (ii) the expiration of regulatory exclusivity for a licensed product in a country, and (iii) fifteen years after the first commercial sale of a licensed product in a major market country. Pfizer also has the right to terminate the agreement without cause in its entirety or on a per product or per country basis. The agreement may also be terminated by either party based on an uncured material breach by the other party or the bankruptcy of the other party. The agreement will also terminate if the Company is unable to identify any lead candidates for development within a specified period of time or if Pfizer elects not to advance a lead candidate beyond a certain development milestone within a specified period of time. Upon termination for any reason, the license granted by the Company to Pfizer to develop, manufacture and commercialize licensed products under the agreement will automatically terminate. Upon termination by the Company for cause or by Pfizer without cause for any licensed product or licensed products in any country or countries, the Company will have the right to negotiate with Pfizer to obtain a non-exclusive, royalty-bearing license under certain technology controlled by Pfizer to develop, manufacture and commercialize the licensed product or licensed products in the terminated country or countries. Following termination by the Company for Pfizer’s material breach, Pfizer will not be permitted to research, develop, manufacture or commercialize ZFPs that specifically bind to the C 9 ORF 72 gene for a period of time. Following termination by Pfizer for the Company’s material breach, the Company will not be permitted to research, develop, manufacture or commercialize ZFPs that specifically bind to the C 9 ORF 72 gene for a period of time. The Company has identified the performance obligations within this agreement as a license to the technology and on-going research services. The Company concluded that the license is not discrete as it does not have stand-alone value to Pfizer apart from the services to be performed by the Company pursuant to the agreement. As a result, the Company recognizes revenue from the upfront payment based on proportional performance of the on-going services, over the estimated period the Company will perform research services. The estimation of progress towards the satisfaction of its performance obligation and project cost is reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables. As of September 30, 2019 and December 31, 2018 , the Company had deferred revenue of $8.3 million and $9.8 million , respectively, related to this agreement. Revenues recognized under the agreement for the three and nine months ended September 30, 2019 and 2018 were as follows (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Recognition of upfront fee related to Pfizer C9ORF72 agreement $ 468 $ 394 $ 1,538 $ 1,470 Sanofi Genzyme In January 2014, the Company entered into an exclusive worldwide collaboration and license agreement to develop therapeutics for hemoglobinopathies, focused on beta thalassemia and sickle cell disease (“SCD”). The agreement was originally signed with Biogen MA Inc., who subsequently assigned it to Bioverativ Inc., which was later acquired by Sanofi. Under the agreement, the Company is jointly conducting two research programs: the beta thalassemia program and the SCD program. In the beta thalassemia program, the Company is responsible for all discovery, research and development activities through the first human clinical trial. In the SCD program, both parties are responsible for research and development activities through the submission of an investigational new drug (“IND”) application for ZFP therapeutics intended to treat SCD. Under both programs, Sanofi is responsible for subsequent worldwide clinical development, manufacturing and commercialization of licensed products developed under the agreement. At the end of the specified research terms for each program or under certain specified circumstances, Sanofi has the right to step in and take over any of the Company’s remaining activities. Furthermore, the Company has an option to co-promote in the U.S. any licensed products to treat beta thalassemia and SCD developed under the agreement, and Sanofi will compensate the Company for such co-promotion activities. Subject to the terms of the agreement, the Company has granted Sanofi an exclusive, royalty-bearing license, with the right to grant sublicenses, to use certain ZFP and other technology controlled by the Company for the purpose of researching, developing, manufacturing and commercializing licensed products developed under the agreement. The Company also granted Sanofi a non-exclusive worldwide, royalty-free fully paid license with the right to grant sublicenses, under the Company’s interest in certain other intellectual property developed pursuant to the agreement. During the term of the agreement, the Company is not permitted to research, develop, manufacture or commercialize, outside of the agreement, certain gene therapy products that target genes relevant to the licensed products. Under the agreement, the Company received an upfront license fee of $20.0 million and is eligible to receive development and sales milestone payments upon the achievement of specified regulatory, clinical development and sales milestones. In addition, the Company will also be eligible to receive up to $115.8 million in payments upon the achievement of specified clinical development and regulatory milestones, as well as up to $160.5 million in payments upon the achievement of specified sales milestones. The total amount of potential regulatory, clinical development and sales milestone payments, assuming the achievement of all specified milestones in the agreement, is up to $276.3 million . In addition, the Company will receive royalty payments for each licensed product that are a tiered double-digit percentage of annual net sales of each product. Sanofi reimburses Sangamo for agreed upon costs incurred in connection with research and development activities conducted by Sangamo. To date, a $6.0 million milestone has been achieved, however no products have been approved and therefore no royalty fees have been earned under the Sanofi agreement. The agreement may be terminated by (i) the Company or Sanofi for the uncured material breach of the other party, (ii) the Company or Sanofi for the bankruptcy or other insolvency proceeding of the other party; (iii) Sanofi, upon 180 days’ advance written notice to the Company and (iv) Sanofi, for certain safety reasons upon written notice to, and after consultation with, the Company. As a result, actual future milestone payments could be lower than the amounts stated above. All contingent payments under the agreement, when earned, will be non-refundable and non-creditable. The transaction price of $75.7 million includes the upfront license fee of $20.0 million and $55.7 million estimated research service costs for identified research projects over the estimated performance period, as all unachieved milestone amounts are fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including the fact that achievement of the milestones at this time is uncertain and contingent upon future periods when the uncertainty related to the variable consideration is resolved. The Company will re-evaluate the transaction price, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. None of the clinical or regulatory milestones have been included in the transaction price. The Company has identified the performance obligations within this arrangement as a license to the technology and on-going research services activities. The Company concluded that the license is not discrete as it does not have stand-alone value to Sanofi apart from the research services to be performed pursuant to the agreement. As a result, the Company recognizes revenue from the upfront payment based on proportional performance of the ongoing services through 2022, the estimated period the Company will perform research services. The estimation of progress towards the satisfaction of performance obligation and project cost is reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables. As of September 30, 2019 and December 31, 2018 , the Company had deferred revenue of $2.0 million and $4.6 million , respectively, related to this agreement. In August 2019, the Company achieved a $6.0 million milestone with Sanofi upon dosing of the third subject in the ST-400 Beta-thalassemia Phase I clinical trial. This milestone was recognized as revenue during the three and nine months ended September 30, 2019. Revenues recognized under the agreement, excluding the milestone revenue, for the three and nine months ended September 30, 2019 and 2018 were as follows (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Revenue related to Sanofi agreement: Recognition of upfront fee $ 940 $ 1,094 $ 2,594 $ 3,432 Research services 1,814 1,146 5,169 7,707 Total $ 2,754 $ 2,240 $ 7,763 $ 11,139 California Institute for Regenerative Medicine In May 2018, the California Institute for Regenerative Medicine (“CIRM”) granted a Strategic Partnership Award for $8.0 million to fund the clinical studies of a potentially curative ZFP therapeutic for the treatment of beta thalassemia based on the application of Sangamo’s ZFN genome editing technology. The grant exists through December 31, 2022 and provides matching funds to support the evaluate ST-400, a gene-edited cell therapy candidate for people with transfusion-dependent beta thalassemia. As of September 30, 2019 and December 31, 2018 , the Company had received $5.2 million and $1.7 million , respectively, under the award. Under the terms of the CIRM grants, the Company is obligated to pay royalties and licensing fees based on a low single digit royalty percentage on net sales of CIRM-funded product candidates or CIRM-funded technology. The Company has the option to decline any and all amounts awarded by CIRM and as an alternative to revenue sharing, the Company has the option to convert the award to a loan. No such election has been made as of the date of the issuance of these financial statements. In the event that the Company terminates a CIRM-funded clinical trial, it will be obligated to repay the remaining CIRM funds on hand. Therefore, as of September 30, 2019 and December 31, 2018 , the $5.5 million and $1.8 million , respectively, including interest, related to this award are recorded as a loan in other long-term liabilities on the accompanying Condensed Consolidated Balance Sheets as the Company does not expect to repay these amounts with the next 12 months.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES The Company maintains deferred tax assets that reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. These deferred tax assets include net operating loss carryforwards, research credits and capitalized research and development costs. Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain based on Sangamo’s history of losses. Accordingly, the Company’s net deferred tax assets have been fully offset by a valuation allowance. Utilization of operating losses and credits may be subject to substantial annual limitation due to ownership change provisions of the Internal Revenue Code of 1986, as amended and similar state provisions. The annual limitation may result in the expiration of net operating losses and credits before utilization.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION The following table shows total stock-based compensation expense included in the Condensed Consolidated Statements of Operations for the three and nine months ended September 30, 2019 and 2018 (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Research and development $ 2,268 $ 2,093 $ 7,329 $ 5,972 General and administrative 2,433 1,717 6,762 4,402 Total stock-based compensation expense $ 4,701 $ 3,810 $ 14,091 $ 10,374

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Leases Sangamo occupies approximately 87,700 square feet of office and research and development laboratory facilities in Brisbane, CA pursuant to a lease that expires in May 2029 . Sangamo also leases approximately 37,900 square feet of office and laboratory space in Richmond, CA through August 2026. The Company leases approximately 7,700 square feet of additional research and office space located in Richmond, CA pursuant to a lease that expires in December 2019. In addition, the Company leases two properties in Valbonne, France. The first lease is for approximately 14,036 square feet of research and office space that expires in June 2025 . The second lease, which commenced on April 1, 2019 , is for approximately 6,800 square feet of office space and expires in March 2028 . Certain of these leases also include renewal options at the election of the Company to renew or extend the lease for an additional five to ten years . These optional periods have not been considered in the determination of the ROU assets or lease liabilities associated with these leases as the Company did not consider it reasonably certain it would exercise the options. With respect to the Brisbane lease, the commencement date for approximately 35,080 square feet of the office space occurred in January 2019 while the commencement date for the remaining approximately 52,620 square feet occurred in June 2019. The Company has the right to make tenant improvements, including the addition of laboratory space, with a lease incentive allowance of $6.8 million on the first portion of the space occupied and $10.2 million on the portion of the lease that commenced in June 2019. The Company performed evaluations of its contracts and determined each of its identified leases are operating leases. For the three and nine months ended September 30, 2019 , the Company incurred $2.6 million and $5.3 million , respectively, of lease costs included in operating expenses in the Condensed Consolidated Statements of Operations in relation to these operating leases. Variable lease expense was $0.6 million and $1.2 million for the three and nine months ended September 30, 2019 , respectively, and was not included in the measurement of the Company’s operating ROU assets and lease liabilities. The variable expense consists primarily of the Company’s proportionate share of operating expenses, property taxes and insurance and is classified as lease expense due to the Company’s election to not separate lease and non-lease components. Cash paid for amounts included in the measurement of operating lease liabilities for the nine months ended September 30, 2019 was $2.0 million and was included in net cash used in operating activities in the Company’s Condensed Consolidated Statements of Cash Flow. As of September 30, 2019 , the maturities of the Company’s operating lease liabilities were as follows (in thousands): Total Three months ending December 31, 2019 $ 1,073 2020 6,055 2021 6,097 2022 6,165 2023 6,243 Thereafter 31,946 Total lease payments 57,579 Less: Imputed interest (13,976 ) Total $ 43,603 Reported as of September 30, 2019: Operating lease liabilities - current (included in Accounts payable and accrued liabilities on the Condensed Consolidated Balance Sheet) $ 2,994 Operating lease liabilities - long-term 40,609 Total $ 43,603 As of September 30, 2019 , the weighted-average remaining lease term is 9.1 years and the weighted-average incremental borrowing rate used to determine the operating lease liability was 6.9% for the Company’s operating leases. The Company does not have any financing leases. Contingencies Sangamo is not party to any material pending legal proceedings or contingencies. From time to time, the Company may be involved in legal proceedings arising in the ordinary course of business.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY Common Stock In April 2019 , Sangamo completed an underwritten public offering of its common stock, in which the Company sold an aggregate of 12.7 million shares of its common stock at a public offering price of $11.50 per share. The net proceeds to Sangamo from the sale of shares in this offering, after deducting underwriting discounts and commissions and other estimated offering expenses, were approximately $136.3 million . In April 2018 , Sangamo completed an underwritten public offering of its common stock, in which the Company sold an aggregate of 14.2 million shares of its common stock at a public offering price of $16.25 per share. The net proceeds to Sangamo from the sale of shares in this offering, after deducting underwriting discounts and commissions and other estimated offering expenses, were approximately $215.8 million . At-the-Market Offering Agreement In May 2017, the Company entered into an amended and restated “at-the-market” offering program sales agreement with Cowen and Company, LLC (“Cowen”), pursuant to which the Company may issue and sell from time to time up to $75.0 million of the Company’s common stock through Cowen as the sales agent (the “ATM Agreement”). Sales of the Company’s common stock, if any, will be made at market prices by any method that is deemed to be an “at-the-market offering” as defined in Rule 415 under the Securities Act of 1933, as amended. As of September 30, 2019 , the Company has not sold any common stock under the ATM Agreement and the full $75.0 million remained available for sale, subject to certain conditions as specified in the agreement.

Acquisition of Sangamo Therapeu

Acquisition of Sangamo Therapeutics France S.A.S.	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Acquisition of Sangamo Therapeutics France S.A.S.	ACQUISITION OF SANGAMO THERAPEUTICS FRANCE S.A.S. On July 20, 2018, Sangamo entered into various agreements with the goal of eventually acquiring 100% of TxCell’s share capital. The Company entered into a Share Purchase Agreement (“SPA”) with certain shareholders of TxCell, pursuant to which it acquired 13,519,036 ordinary shares of TxCell (“TxCell Ordinary Shares”) as part of a block transaction that closed on October 1, 2018 (the “Acquisition Date”). Additionally, the Company and TxCell entered into a Tender Offer Agreement pursuant to which it agreed to acquire 11,528,635 TxCell Ordinary Shares for the same price per share via a cash tender offer that closed on November 23, 2018. Following the block transaction, cash tender offer, and other open market purchases of shares, the Company owned 98.2% of the TxCell Ordinary Shares as of December 31, 2018 (or 25,047,671 TxCell Ordinary Shares). In addition to the SPA and the tender offer agreement, the Company also entered into arrangements with the holders of approximately 477,000 “free shares” of TxCell pursuant to which the Company has the right to purchase such shares from the holders thereof (a call option) and such holders have the right to sell to the Company such shares from time to time through mid-2021 (a put option) (collectively the “Free Shares Options”). In June 2019, TxCell became a sociéte par actions simplifiée (S.A.S.) and was renamed “Sangamo Therapeutics France.” During the three months ended September 30, 2019, the Company acquired approximately 111,000 vested free shares, including 52,700 from a former executive of TxCell who is now an executive of Sangamo, pursuant to the exercise of the Free Shares Options for approximately $0.3 million of cash, increasing its ownership of the TxCell Ordinary Shares to 98.7% as of September 30, 2019. At the Acquisition Date, the fair value of the Free Shares Options was estimated to be a liability of $0.2 million . See "Note 2 - Fair Value Measurement -Free Shares Asset/Liability" for information regarding the valuation method. The fair value of the Free Shares Options will vary based on future changes in the Company’s stock price during the option period. The fair value of the Free Shares Options was estimated to be an asset of $0.2 million as of September 30, 2019 . The acquisition of Sangamo France was accounted for as a business combination in accordance with ASC Topic 805, Business Combinations . The operating results of Sangamo France after the Acquisition Date have been included in the Company’s Condensed Consolidated Statements of Operations. There were no goodwill impairments during the nine months ended September 30, 2019 or during 2018 and, as noted below, substantially all of the non-controlling interest on the Acquisition Date was subsequently acquired by the Company and, accordingly, substantially all of the goodwill is allocated to the Company as of September 30, 2019 and December 31, 2018 . The following table summarizes the estimated consideration transferred and the fair value of the net assets acquired as of the Acquisition Date (in thousands): October 1, 2018 Consideration transferred $ 45,911 Fair value of non-controlling interest 35,829 Fair value of TxCell $ 81,740 Cash $ 4,779 Current assets 2,427 Property and equipment 1,857 IPR&D 55,019 Other assets 155 Current liabilities (9,761 ) Assumed debt liabilities (4,933 ) Deferred tax liability, net (6,798 ) Fair value of net identifiable assets acquired 42,745 Goodwill 38,995 Total fair value of net assets acquired $ 81,740 Non-Controlling Interest The fair value of the non-controlling interest at the Acquisition Date was based on the $2.99 acquisition price per share for the 11,981,867 TxCell Ordinary Shares that were not purchased by the Company in the block transaction on the Acquisition Date. Subsequent to the Acquisition Date and through December 31, 2018, the Company acquired 11,528,635 TxCell Ordinary Shares, which when aggregated with the 13,519,036 TxCell Ordinary Shares acquired at the Acquisition Date, resulted in the Company owning 98.2% of all TxCell Ordinary Shares as of December 31, 2018. During the three months ended September 30, 2019 , the Company acquired approximately 111,000 vested free shares for approximately $0.3 million of cash, pursuant to the exercise of the Free Shares Options, increasing its ownership of the TxCell Ordinary Shares to 98.7% as of September 30, 2019 . The fair value of the remaining non-controlling was determined based on the number of outstanding shares comprising the non-controlling interest and the $2.99 acquisition price per share as of the Acquisition Date. The non-controlling interest is presented as a component of stockholders equity on the Company’s Condensed Consolidated Balance Sheets. Non-controlling interest as of September 30, 2019 was as follows (in thousands): Non-controlling interest at December 31, 2018 $ 739 Fair value of additional shares acquired (321 ) Loss attributable to non-controlling interest (179 ) Non-controlling interest at September 30, 2019 $ 239

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:16px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">SUBSEQUENT EVENTS</font></div><div style="line-height:120%;padding-top:8px;text-indent:48px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;background-color:#ffff00;">[OPEN THROUGH FILING DATE]</font></div></div>

Organization, Basis of Presen_2

Organization, Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) for interim financial information and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included. Operating results for the three and nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 . The Condensed Consolidated Balance Sheet data at December 31, 2018 was derived from the audited consolidated financial statements included in Sangamo’s Annual Report on Form 10-K for the year ended December 31, 2018 (the “ 2018 Annual Report”) as filed with the SEC on March 1, 2019. The accompanying Condensed Consolidated Financial Statements and related financial information should be read in conjunction with the audited financial statements and footnotes thereto for the year ended December 31, 2018 , included in the 2018 Annual Report.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and the accompanying notes. On an ongoing basis, management evaluates its estimates including critical accounting policies or estimates related to revenue recognition, clinical trial accruals, fair value of assets and liabilities, including from acquisitions, and stock-based compensation. Estimates are based on historical experience and on various other market specific and other relevant assumptions that the Company believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. In March 2019, the Company recorded an adjustment to revenue related to a change in estimate in connection with the hemophilia A collaboration agreement with Pfizer Inc. (“Pfizer”). This adjustment was a direct result of the increase in project scope during the first quarter of 2019 and the corresponding costs which resulted in a decrease in the measure of proportional performance. This adjustment decreased revenue by $3.0 million , increased net loss by $3.0 million and increased the Company’s basic net loss per share by $0.03 for the nine months ended September 30, 2019 .
Foreign Currency Translation	Foreign Currency Translation The functional currency of the Company’s foreign subsidiaries is primarily the Euro. Assets and liabilities denominated in foreign currencies are translated to U.S. dollars using the exchange rates at the balance sheet date. Foreign currency translation adjustments are recorded as a component of Accumulated Other Comprehensive Income (Loss) (“AOCI”) within stockholders’ equity. Revenues and expenses from the Company’s foreign subsidiaries are translated using the monthly average exchange rates in effect during the period in which the transactions occur. Foreign currency transaction gains and losses are recorded in interest and other income, net, on the Company’s Condensed Consolidated Statements of Operations.
Reclassifications	Reclassifications Certain prior period amounts in the accompanying Condensed Consolidated Financial Statements have been reclassified to conform to the current period presentation. These reclassifications had no effect on the reported results of operations. The Company reclassified $0.6 million from Intangible assets to Other non-current assets on the Condensed Consolidated Balance Sheet as of December 31, 2018 .
Cash and Cash Equivalents	Cash and Cash Equivalents Sangamo considers all highly-liquid investments purchased with original maturities of three months or less at the purchase date to be cash equivalents. Cash and cash equivalents consist of cash, deposits in demand money market accounts and commercial paper.
Marketable Securities	Marketable Securities Sangamo classifies its marketable securities as available-for-sale and records its investments at estimated fair value based on quoted market prices or observable market inputs of almost identical assets, with the unrealized holding gains and losses included in AOCI. The Company’s investments are subject to a periodic impairment review. The Company recognizes an impairment charge, if material; when a decline in the fair value of its investments below the cost basis is judged to be other-than-temporary. The Company considers various factors in determining whether to recognize an impairment charge, including the length of time and extent to which the fair value has been less than the Company’s cost basis, the financial condition and near-term prospects of the investee and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in the market value. Realized gains and losses on available-for-sale securities are included in other income, net, which are determined using the specific identification method.
Concentrations of Risk	Concentrations of Risk Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to a concentration of credit risk to the extent of the fair value recorded in the Condensed Consolidated Balance Sheets. The Company invests cash that is not required for immediate operating needs primarily in highly liquid instruments that bear minimal risk. The Company has established guidelines relating to the quality, diversification, and maturities of securities to enable the Company to manage its credit risk. The Company is exposed to credit risk in the event of a default by the financial institutions holding its cash, cash equivalents and investments and issuers of investments to the extent recorded on the Condensed Consolidated Balance Sheets. Certain materials and key components that the Company utilizes in its operations are obtained through single suppliers. Since the suppliers of key components and materials must be named in an investigational new drug application filed with the U.S. Food and Drug Administration for a product, significant delays can occur if the qualification of a new supplier is required. If delivery of material from the Company’s suppliers were interrupted for any reason, the Company may be unable to supply any of its product candidates for clinical trials.
Fair Value Measurements	Fair Value Measurements The carrying amounts for financial instruments consisting of cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate fair value due to their short maturities. Marketable securities are stated at their estimated fair values. The free share asset/liability is measured using a binomial-lattice pricing model and is reviewed each reporting period and adjusted, as needed and is expected to approximate fair value.
Leases	Leases The Company determines if an arrangement is or contains a lease at inception by assessing whether the arrangement contains an identified asset and whether it has the right to control the identified asset. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Lease liabilities are recognized at the lease commencement date based on the present value of future lease payments over the lease term. ROU assets are based on the measurement of the lease liability and also include any lease payments made prior to or on lease commencement and exclude lease incentives and initial direct costs incurred, as applicable. As the implicit rate in the Company’s leases is generally unknown, the Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of remaining lease payments. The incremental borrowing rate represents an estimate of the interest rate the Company would incur at lease commencement to borrow an amount equal to the lease payments on a collateralized basis over the term of a lease in a similar economic environment. The Company gives consideration to its credit risk, term of the lease, total lease payments and adjusts for the impacts of collateral, as necessary, when calculating its incremental borrowing rates. The lease terms may include options to extend or terminate the lease when it is reasonably certain the Company will exercise any such options. Rent expense for the Company’s operating leases is recognized on a straight-line basis over the lease term. The Company has elected to not separate lease and non-lease components for its real estate and copier leases and, as a result, accounts for any lease and non-lease components as a single lease component. The Company has also elected to not apply the recognition requirement to any leases with a term of 12 months or less and does not include an option to purchase the underlying asset that the Company is reasonably certain to exercise.
Revenue Recognition	Revenue Recognition Effective January 1, 2018, the Company adopted the provisions of Accounting Standards Codification (“ASC”) Topic 606 - Revenue from Contracts with Customers (“ASC Topic 606”) using the modified retrospective method, resulting in a change to its accounting policy for revenue recognition. ASC Topic 606 establishes a unified model to determine how revenue is recognized. The Company’s contract revenues consist of strategic partnering collaboration agreements and research activity grants and licensing. Research and licensing agreements typically include upfront signing or license fees, cost reimbursements, research services, minimum sublicense fees, milestone payments and royalties on future licensee’s product sales. The Company has both fixed and variable consideration. Non-refundable upfront fees and funding of research and development activities are considered fixed, while milestone payments are identified as variable consideration. Sangamo’s research grants are typically multi-year agreements and provide for the reimbursement of qualified expenses for research and development as defined under the terms of the grant agreement. Revenues under research grant agreements are recognized when the related qualified research expenses are incurred. Deferred revenue represents the portion of research or license payments received and incurred but not earned. In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account in ASC Topic 606. The Company’s performance obligations include license rights, development services and services associated with regulatory submission and approval processes. Revenues from research services are made under strategic partnering agreements and collaborations are generally recognized as the services are provided while revenues from non-refundable upfront fees are recognized over time either by measuring progress towards satisfaction of the relevant performance obligation, using input method or on a straight-line basis when a performance obligation is assumed to be satisfied evenly over a period of time (or when the entity has a stand-ready obligation). Significant management judgment is required to determine the level of effort required under an arrangement and the period over which the Company expects to complete its performance obligations under the arrangement which may include reimbursement rates for personnel costs, external reimbursable costs, estimated period of performance and estimating the progress towards the satisfaction of performance obligation. If the Company cannot reasonably estimate when its performance obligations either are completed or become inconsequential, then revenue recognition is deferred until the Company can reasonably make such estimates. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint and, if necessary, adjusts its estimate of the overall transaction price. Revenue is then recognized over the remaining estimated period of performance using the cumulative catch-up method. The estimated period of performance and project costs, such as personnel and manufacturing cost, are reviewed quarterly and adjusted, as needed, to reflect the Company’s current assumptions regarding the timing of its deliverables. As part of the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the stand-alone selling price of each performance obligation identified in the contract. The Company uses key assumptions to determine the stand-alone selling price which may include forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success. Related costs and expenses under these arrangements have historically approximated the revenues recognized. For the nine months ended September 30, 2019 , revenues related to Kite Pharma, Inc. (“Kite”), a wholly-owned subsidiary of Gilead Sciences, Inc., Bioverativ Inc., (now Sanofi Genzyme, a global business unit of Sanofi S.A. (“Sanofi”)), and the Company's hemophilia A collaboration agreement with Pfizer represented 55% , 29% and 11% , respectively, of the Company’s total revenue. For the three months ended September 30, 2019 , revenues related to Kite, Sanofi and the Company's hemophilia A collaboration agreement with Pfizer represented 40% , 40% and 16% , respectively, of the Company’s total revenue. During the nine months ended September 30, 2018 , revenues related to the Company's hemophilia A collaboration agreement with Pfizer, Kite and Sanofi represented 46% , 29% and 19% respectively, of the Company’s total revenue. For the three months ended September 30, 2018 , revenues related to the Company's hemophilia A collaboration agreement with Pfizer, Kite and Sanofi represented 44% , 38% and 10% , respectively, of the Company’s total revenue. Receivables from collaborations are typically unsecured and are concentrated in the biopharmaceutical industry. Accordingly, the Company may be exposed to credit risk generally associated with biopharmaceutical companies or specific to its collaboration agreements. To date, the Company has not experienced any losses related to these receivables. Funds received from third parties under contract or grant arrangements are recorded as revenue if the Company is deemed to be the principal participant in the arrangements because the activities under the contracts or grants are part of the Company’s development programs. Contract funds received are not refundable and are recognized when the related qualified research and development costs are incurred and there is reasonable assurance that the funds will be received. Funds received in advance are recorded as deferred revenue.
Recent Accounting Pronouncements	Not yet adopted Collaborative Arrangements In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (ASC Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 (“ASC Topic 808”), which clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC Topic 606 when the counterparty is a customer. In addition, ASC Topic 808 precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. This guidance will be effective for the Company beginning January 1, 2020. The Company is currently evaluating the impact of the adoption of this standard on its consolidated financial statements. Goodwill Impairment Testing In January 2017, the FASB issued ASU No. 2017 -4 , Intangibles – Goodwill and Other (Topic 350): Simplifying the Test of Goodwill Impairment (“ASU 2017 -4 ”). The new guidance simplifies the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. ASU 2017 -4 requires goodwill impairment to be measured as the amount by which a reporting unit’s carrying amount exceeds its fair value, not to exceed the carrying amount of its goodwill. ASU 2017 -4 requires prospective application and is effective for annual periods beginning after December 15, 2019. ASU 2017 -4 will require the Company to amend its methodology for determining any goodwill impairment beginning in 2020. Recent Accounting Pronouncements Recently Adopted Simplified Disclosure In August 2018, the SEC adopted amendments to certain disclosure requirements in Securities Act Release No. 33-10532, Disclosure Update and Simplification , as updated. These amendments eliminate, modify, or integrate into other SEC requirements certain disclosure rules. Among the amendments is the requirement to present an analysis of changes in stockholders’ equity in the interim financial statements included in quarterly reports on Form 10-Q. The analysis, which can be presented as a footnote or separate statement, is required for the current and comparative quarter and year-to-date interim periods. The amendments are effective for all filings made on or after November 5, 2018. As such, the Company adopted these SEC amendments on November 5, 2018 and has presented the analysis of changes in stockholders’ equity in these interim financial statements for September 30, 2019 and 2018 presented in this Quarterly Report on Form 10-Q. The Company’s adoption of these SEC amendments had no material effect on the Company’s reporting of financial position, results of operations, cash flows or stockholders’ equity. Accounting for Leases In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016 -2 , Leases (“ASC Topic 842”). ASC Topic 842 amends a number of aspects of lease accounting, including requiring lessees to recognize almost all leases with a term greater than one year as a ROU asset and corresponding liability, measured at the present value of the lease payments. On January 1, 2019, the Company adopted ASC Topic 842 using the modified retrospective approach with a cumulative-effect adjustment of $0.9 million reflected as a decrease to the opening balance of accumulated deficit as of the adoption date. Results for the three and nine months ended September 30, 2019 are presented under ASC Topic 842. No prior period amounts were adjusted and continue to be reported in accordance with previous lease guidance, ASC Topic 840 — Leases (“ASC Topic 840”). ASC Topic 842 provides a number of optional practical expedients in transition. The Company elected the practical expedients to not reassess its prior conclusions about lease identification under the new standard, to not reassess lease classification, and to not reassess initial direct costs. The Company did not elect the practical expedient allowing the use-of-hindsight which would require the Company to reassess the lease term of its leases based on all facts and circumstances through the effective date and did not elect the practical expedient pertaining to land easements as this is not applicable to the current contract portfolio.

Organization, Basis of Presen_3

Organization, Basis of Presentation and Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Impact of the adoption of ASC Topic 842	The impact of the adoption of ASC Topic 842 on the accompanying Condensed Consolidated Balance Sheet as of January 1, 2019 was as follows (in thousands): December 31, 2018 Adjustments Due to the Adoption of ASC Topic 842 January 1, 2019 Assets: Property and equipment, net $ 78,723 $ (62,500 ) $ 16,223 Operating lease right-of-use assets — 8,753 8,753 Prepaid rent — 36,025 36,025 Liabilities: Operating lease liabilities - current (1) — 1,408 1,408 Deferred rent (1) 271 (271 ) — Build-to-suit lease obligation (2) 27,689 (27,689 ) — Operating lease liabilities - long-term (2) — 7,933 7,933 Accumulated deficit (562,696 ) 897 (561,799 ) ___________________ (1) Operating lease liabilities – current and deferred rent are included in accounts payable and accrued liabilities on the Condensed Consolidated Balance Sheets. (2) Build-to-suit lease obligation and operating lease liabilities – long-term are included in long-term portion of lease liabilities on the Condensed Consolidated Balance Sheets.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Summary of Fair Value Measurements of Cash Equivalents, Available-for-Sale Marketable Securities and Free Share Asset/Liability	The fair value measurements of the Company’s cash equivalents, available-for-sale marketable securities and the free share asset/liability are identified at the following levels within the fair value hierarchy (in thousands): September 30, 2019 Total Level 1 Level 2 Level 3 Assets: Cash equivalents: Money market funds $ 77,213 $ 77,213 $ — $ — Total 77,213 77,213 — — Marketable securities: Commercial paper securities 180,812 — 180,812 — Corporate debt securities 71,114 — 71,114 — U.S. government-sponsored entity debt securities 41,424 — 41,424 — Total 293,350 — 293,350 — Total cash equivalents and marketable securities $ 370,563 $ 77,213 $ 293,350 $ — Free shares asset $ 239 $ — $ — $ 239 December 31, 2018 Total Level 1 Level 2 Level 3 Assets: Cash equivalents: Money market funds $ 103,291 $ 103,291 $ — $ — Total 103,291 103,291 — — Marketable securities: Commercial paper securities 177,224 — 177,224 — Corporate debt securities 63,870 — 63,870 — U.S. government-sponsored entity debt securities 18,621 — 18,621 — Total 259,715 — 259,715 — Total cash equivalents and marketable securities $ 363,006 $ 103,291 $ 259,715 $ — Liabilities: Free shares liability $ 154 $ — $ — $ 154
Summary of Estimated Fair Value of Free Shares Valuation Assumptions	Free Shares valuation assumptions: September 30, December 31, 2018 Sangamo Stock Price (USD) $ 9.05 $ 11.48 TxCell Stock Price (EUR) € 2.23 € 2.58 EUR / USD Exchange Rate 0.91 0.87 Estimated Correlation Sangamo and TxCell Stock Prices 100.0% — Sangamo Stock Price (USD) Volatility Estimate 75.0% 79.9% TxCell Stock Price (EUR) Volatility Estimate 75.0% 8.6% EUR / USD Exchange Rate Volatility Estimate 6.8% 7.7% Risk Free Rate and Cost of Debt by Expected Exercise Date Varies Varies

Cash and Marketable Securities

Cash and Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Schedule of Cash and Cash Equivalents	A reconciliation of cash, cash equivalents and restricted cash reported within the Condensed Consolidated Balance Sheets to the amounts reported within the accompanying Condensed Consolidated Statements of Cash Flows was as follows (in thousands): September 30, December 31, September 30, December 31, Cash and cash equivalents $ 114,291 $ 140,418 $ 39,298 $ 49,826 Restricted cash included in Restricted cash, current portion 2,000 — — — Restricted cash included in Non-current restricted cash 1,500 3,500 79,941 3,500 Cash, cash equivalents and restricted cash as reported within the accompanying Condensed Consolidated Statements of Cash Flows $ 117,791 $ 143,918 $ 119,239 $ 53,326
Restrictions on Cash and Cash Equivalents	A reconciliation of cash, cash equivalents and restricted cash reported within the Condensed Consolidated Balance Sheets to the amounts reported within the accompanying Condensed Consolidated Statements of Cash Flows was as follows (in thousands): September 30, December 31, September 30, December 31, Cash and cash equivalents $ 114,291 $ 140,418 $ 39,298 $ 49,826 Restricted cash included in Restricted cash, current portion 2,000 — — — Restricted cash included in Non-current restricted cash 1,500 3,500 79,941 3,500 Cash, cash equivalents and restricted cash as reported within the accompanying Condensed Consolidated Statements of Cash Flows $ 117,791 $ 143,918 $ 119,239 $ 53,326
Marketable Securities	The table below summarizes the Company’s cash equivalents and available-for-sale securities (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Estimated Fair Value September 30, 2019 Assets Cash equivalents: Money market funds $ 77,213 $ — $ — $ 77,213 Total 77,213 — — 77,213 Available-for-sale securities: Commercial paper securities 180,590 224 (2 ) 180,812 Corporate debt securities 70,947 167 — 71,114 U.S. government-sponsored entity debt securities 41,394 30 — 41,424 Total 292,931 421 (2 ) 293,350 Total cash equivalents and available-for-sale securities $ 370,144 $ 421 $ (2 ) $ 370,563 December 31, 2018 Assets Cash equivalents: Money market funds $ 103,291 $ — $ — $ 103,291 Total 103,291 — — 103,291 Available-for-sale securities: Commercial paper securities 177,353 — (129 ) 177,224 Corporate debt securities 63,981 — (111 ) 63,870 U.S. government-sponsored entity debt securities 18,640 — (19 ) 18,621 Total 259,974 — (259 ) 259,715 Total cash equivalents and available-for-sale securities $ 363,265 $ — $ (259 ) $ 363,006
Fair value of investments available-for-sale	The fair value of investments available-for-sale by contractual maturity were as follows (in thousands): September 30, December 31, Maturing in one year or less $ 240,561 $ 259,715 Maturing after one year through five years 52,789 — Total $ 293,350 $ 259,715

Major Customers, Partnerships_2

Major Customers, Partnerships and Strategic Alliances (Tables)	9 Months Ended
	Sep. 30, 2019
Kite Pharma Inc
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenues Recognized under Agreement	Revenues recognized under the agreement for the three and nine months ended September 30, 2019 and 2018 were as follows (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Revenue related to Kite agreement: Recognition of license and stand-ready fee $ 6,296 $ 6,296 $ 18,682 $ 12,249 Research services 2,565 2,732 7,551 4,295 Total $ 8,861 $ 9,028 $ 26,233 $ 16,544
Pfizer SB-525
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenues Recognized under Agreement	Revenues recognized under the agreement for the three and nine months ended September 30, 2019 and 2018 were as follows (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Recognition of upfront fee related to Pfizer SB-525 agreement $ 3,440 $ 10,421 $ 5,035 $ 26,262
Pfizer
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenues Recognized under Agreement	Revenues recognized under the agreement for the three and nine months ended September 30, 2019 and 2018 were as follows (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Recognition of upfront fee related to Pfizer C9ORF72 agreement $ 468 $ 394 $ 1,538 $ 1,470
Sanofi
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenues Recognized under Agreement	Revenues recognized under the agreement, excluding the milestone revenue, for the three and nine months ended September 30, 2019 and 2018 were as follows (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Revenue related to Sanofi agreement: Recognition of upfront fee $ 940 $ 1,094 $ 2,594 $ 3,432 Research services 1,814 1,146 5,169 7,707 Total $ 2,754 $ 2,240 $ 7,763 $ 11,139

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Expense	The following table shows total stock-based compensation expense included in the Condensed Consolidated Statements of Operations for the three and nine months ended September 30, 2019 and 2018 (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Research and development $ 2,268 $ 2,093 $ 7,329 $ 5,972 General and administrative 2,433 1,717 6,762 4,402 Total stock-based compensation expense $ 4,701 $ 3,810 $ 14,091 $ 10,374

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Summary of Maturities of Operating Lease Liabilities	As of September 30, 2019 , the maturities of the Company’s operating lease liabilities were as follows (in thousands): Total Three months ending December 31, 2019 $ 1,073 2020 6,055 2021 6,097 2022 6,165 2023 6,243 Thereafter 31,946 Total lease payments 57,579 Less: Imputed interest (13,976 ) Total $ 43,603 Reported as of September 30, 2019: Operating lease liabilities - current (included in Accounts payable and accrued liabilities on the Condensed Consolidated Balance Sheet) $ 2,994 Operating lease liabilities - long-term 40,609 Total $ 43,603

Acquisition of Sangamo Therap_2

Acquisition of Sangamo Therapeutics France S.A.S. (Tables)	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Summary of Estimated Fair Value of Net Assets Acquired	The following table summarizes the estimated consideration transferred and the fair value of the net assets acquired as of the Acquisition Date (in thousands): October 1, 2018 Consideration transferred $ 45,911 Fair value of non-controlling interest 35,829 Fair value of TxCell $ 81,740 Cash $ 4,779 Current assets 2,427 Property and equipment 1,857 IPR&D 55,019 Other assets 155 Current liabilities (9,761 ) Assumed debt liabilities (4,933 ) Deferred tax liability, net (6,798 ) Fair value of net identifiable assets acquired 42,745 Goodwill 38,995 Total fair value of net assets acquired $ 81,740
Summary of Non-controlling Interest	Non-controlling interest as of September 30, 2019 was as follows (in thousands): Non-controlling interest at December 31, 2018 $ 739 Fair value of additional shares acquired (321 ) Loss attributable to non-controlling interest (179 ) Non-controlling interest at September 30, 2019 $ 239

Organization, Basis of Presen_4

Organization, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Jan. 01, 2019
Organization And Summary Of Significant Accounting Policies [Line Items]
Decrease in revenues	$ (21,958)	$ (23,562)	$ (47,577)	$ (57,615)
Increase in net loss	$ 27,361	$ 12,843	$ 99,920	$ 49,670
Topic 842
Organization And Summary Of Significant Accounting Policies [Line Items]
Cumulative-effect adjustment of ASC						$ 897
Pfizer | Customer Concentration Risk | Total revenues
Organization And Summary Of Significant Accounting Policies [Line Items]
Percentage of revenues	16.00%	44.00%	11.00%	46.00%
Kite Pharma Inc
Organization And Summary Of Significant Accounting Policies [Line Items]
Decrease in revenues	$ (8,861)	$ (9,028)	$ (26,233)	$ (16,544)
Kite Pharma Inc | Customer Concentration Risk | Total revenues
Organization And Summary Of Significant Accounting Policies [Line Items]
Percentage of revenues	40.00%	38.00%	55.00%	29.00%
Sanofi
Organization And Summary Of Significant Accounting Policies [Line Items]
Decrease in revenues	$ (2,754)	$ (2,240)	$ (7,763)	$ (11,139)
Sanofi | Customer Concentration Risk | Total revenues
Organization And Summary Of Significant Accounting Policies [Line Items]
Percentage of revenues	40.00%	10.00%	29.00%	19.00%
Change in Collaboration Agreement Scope | Collaboration Agreement | Pfizer
Organization And Summary Of Significant Accounting Policies [Line Items]
Decrease in revenues			$ 3,000
Increase in net loss			$ 3,000
Increase in basic net loss per share (Usd per share)			$ 0.03
Other non-current assets
Organization And Summary Of Significant Accounting Policies [Line Items]
Reclassification adjustment					$ 600
Accumulated Deficit
Organization And Summary Of Significant Accounting Policies [Line Items]
Increase in net loss	$ 27,307	$ 12,843	$ 99,741	$ 49,670
Accumulated Deficit | Topic 842
Organization And Summary Of Significant Accounting Policies [Line Items]
Cumulative-effect adjustment of ASC						$ 897

Organization, Basis of Presen_5

Organization, Basis of Presentation and Summary of Significant Accounting Policies - Impact of Adoption of ASC on Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
ASSETS
Property and equipment, net	$ 26,516		$ 78,723
Operating lease right-of-use assets	77,505
Liabilities:
Operating lease liabilities - current	2,994
Deferred rent			271
Operating lease liabilities - long-term	40,609		27,689
Accumulated deficit	$ (661,540)		(562,696)
Topic 842
ASSETS
Property and equipment, net		$ 16,223
Operating lease right-of-use assets		8,753
Prepaid rent		36,025
Liabilities:
Operating lease liabilities - current		1,408
Operating lease liabilities - long-term		7,933
Accumulated deficit		(561,799)
Topic 842 | Adjustments Due to the Adoption of ASC Topic 842
ASSETS
Property and equipment, net		(62,500)
Operating lease right-of-use assets		8,753
Prepaid rent		36,025
Liabilities:
Operating lease liabilities - current		1,408
Deferred rent		(271)
Operating lease liabilities - long-term		7,933
Accumulated deficit		897
Build To Suit Lease
Liabilities:
Operating lease liabilities - long-term			$ 27,689
Build To Suit Lease | Topic 842 | Adjustments Due to the Adoption of ASC Topic 842
Liabilities:
Operating lease liabilities - long-term		$ (27,689)

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Fair Value Measurements of Cash Equivalents, Available-for-Sale Marketable Securities and Free Share Asset/Liability (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	$ 293,350	$ 259,715
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	77,213	103,291
Commercial paper securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	180,812	177,224
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	71,114	63,870
U.S. government-sponsored entity debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	41,424	18,621
Fair value on recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	77,213	103,291
Total marketable securities	293,350	259,715
Total cash equivalents and marketable securities and free shares asset	370,563	363,006
Fair value on recurring basis | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	77,213	103,291
Fair value on recurring basis | Commercial paper securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	180,812	177,224
Fair value on recurring basis | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	71,114	63,870
Fair value on recurring basis | U.S. government-sponsored entity debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	41,424	18,621
Fair value on recurring basis | Free shares asset
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities and free shares asset	239
Fair value on recurring basis | Free shares liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Free shares liability		154
Fair value on recurring basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	77,213	103,291
Total marketable securities	0	0
Total cash equivalents and marketable securities and free shares asset	77,213	103,291
Fair value on recurring basis | Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	77,213	103,291
Fair value on recurring basis | Level 1 | Commercial paper securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	0	0
Fair value on recurring basis | Level 1 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	0	0
Fair value on recurring basis | Level 1 | U.S. government-sponsored entity debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	0	0
Fair value on recurring basis | Level 1 | Free shares asset
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities and free shares asset	0
Fair value on recurring basis | Level 1 | Free shares liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Free shares liability		0
Fair value on recurring basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	0
Total marketable securities	293,350	259,715
Total cash equivalents and marketable securities and free shares asset	293,350	259,715
Fair value on recurring basis | Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	0
Fair value on recurring basis | Level 2 | Commercial paper securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	180,812	177,224
Fair value on recurring basis | Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	71,114	63,870
Fair value on recurring basis | Level 2 | U.S. government-sponsored entity debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	41,424	18,621
Fair value on recurring basis | Level 2 | Free shares asset
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities and free shares asset	0
Fair value on recurring basis | Level 2 | Free shares liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Free shares liability		0
Fair value on recurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	0
Total marketable securities	0	0
Total cash equivalents and marketable securities and free shares asset	0	0
Fair value on recurring basis | Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	0
Fair value on recurring basis | Level 3 | Commercial paper securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	0	0
Fair value on recurring basis | Level 3 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	0	0
Fair value on recurring basis | Level 3 | U.S. government-sponsored entity debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	0	0
Fair value on recurring basis | Level 3 | Free shares asset
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents and marketable securities and free shares asset	$ 239
Fair value on recurring basis | Level 3 | Free shares liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Free shares liability		$ 154

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - TxCell S.A. - USD ($) $ in Millions	Nov. 23, 2018	Oct. 01, 2018	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Number of shares acquired (in shares)		13,519,036	111,000	11,528,635
Share Purchase Agreement and Tender Offer Agreement
Debt Securities, Available-for-sale [Line Items]
Number of free shares held by the holders (in shares)		477,000	477,000		477,000
Estimated fair value liability of free shares		$ 0.2
Number of shares acquired (in shares)	11,528,635		111,000	25,047,671
Cash payments to acquire free shares			$ 0.3
Number of free shares outstanding subject to purchase (in shares)			366,000
Increase in fair value of free shares					$ 0.5
Fair value Of free shares purchased					0.1
Estimated fair value asset of free shares			$ 0.2		$ 0.2
Valuation Technique, Option Pricing Model | Share Purchase Agreement and Tender Offer Agreement
Debt Securities, Available-for-sale [Line Items]
Estimated fair value liability of free shares		$ 0.2		$ 0.2

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Estimated Fair Value of Free Shares Valuation Assumptions (Detail)	Sep. 30, 2019$ / shares€ / shares€ / $	Dec. 31, 2018$ / shares€ / shares€ / $
Stock Price (USD per share)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Free shares measurement input | $ / shares	9.05	11.48
Exchange Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Free shares measurement input | € / $	0.91	0.87
Stock Price Volatility Estimate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Free shares measurement input	75	79.9
EUR / USD Exchange Rate Volatility Estimate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Free shares measurement input	6.8	7.7
TxCell S.A. | Stock Price (USD per share)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Free shares measurement input | € / shares	2.23	2.58
TxCell S.A. | Stock Price Correlation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Free shares measurement input	100	0
TxCell S.A. | Stock Price Volatility Estimate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Free shares measurement input	75	8.6

Cash and Marketable Securitie_2

Cash and Marketable Securities - Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Cash and cash equivalents	$ 114,291	$ 140,418	$ 39,298	$ 49,826
Restricted cash included in Restricted cash, current portion	2,000	0	0	0
Restricted cash included in Non-current restricted cash	1,500	3,500	79,941	3,500
Cash, cash equivalents and restricted cash as reported within the accompanying Condensed Consolidated Statements of Cash Flows	117,791	$ 143,918	$ 119,239	$ 53,326
Letter of credit established as a deposit	$ 3,500

Cash and Marketable Securitie_3

Cash and Marketable Securities - Additional Information (Detail) - USD ($)	1 Months Ended	9 Months Ended		12 Months Ended
	Oct. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Subsequent Event [Line Items]
Letter of credit established as a deposit		$ 3,500,000
Realized losses of available-for-sale securities		0	$ 0
Other-than-temporarily impaired investments		$ 0		$ 0
Subsequent Event
Subsequent Event [Line Items]
Release of restricted cash	$ 2,000,000

Cash and Marketable Securitie_4

Cash and Marketable Securities - Summary of Cash Equivalents and Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
ASSETS
Cash equivalents, Amortized Cost	$ 114,291	$ 140,418	$ 39,298	$ 49,826
Available-for-sale securities, Amortized Cost	292,931	259,974
Available-for-sale securities, Gross Unrealized Gains	421	0
Available-for-sale securities, Gross Unrealized (Losses)	(2)	(259)
Available-for-sale securities, Estimated Fair Value	293,350	259,715
Total cash equivalents and available-for-sale securities, Amortized Cost	370,144	363,265
Total cash equivalents and available-for-sale securities, Gross Unrealized Gains	421	0
Total cash equivalents and available-for-sale securities, Gross Unrealized (Losses)	(2)	(259)
Total cash equivalents and available-for-sale securities, Estimated Fair Value	370,563	363,006
Money market funds
ASSETS
Cash equivalents, Amortized Cost	77,213	103,291
Cash equivalents, Gross Unrealized Gains	0	0
Cash equivalents, Gross Unrealized (Losses)	0	0
Cash equivalents, Estimated Fair Value	77,213	103,291
Cash equivalents
ASSETS
Cash equivalents, Amortized Cost	77,213	103,291
Cash equivalents, Gross Unrealized Gains	0	0
Cash equivalents, Gross Unrealized (Losses)	0	0
Cash equivalents, Estimated Fair Value	77,213	103,291
Commercial paper securities
ASSETS
Available-for-sale securities, Amortized Cost	180,590	177,353
Available-for-sale securities, Gross Unrealized Gains	224	0
Available-for-sale securities, Gross Unrealized (Losses)	(2)	(129)
Available-for-sale securities, Estimated Fair Value	180,812	177,224
Corporate debt securities
ASSETS
Available-for-sale securities, Amortized Cost	70,947	63,981
Available-for-sale securities, Gross Unrealized Gains	167	0
Available-for-sale securities, Gross Unrealized (Losses)	0	(111)
Available-for-sale securities, Estimated Fair Value	71,114	63,870
U.S. government-sponsored entity debt securities
ASSETS
Available-for-sale securities, Amortized Cost	41,394	18,640
Available-for-sale securities, Gross Unrealized Gains	30	0
Available-for-sale securities, Gross Unrealized (Losses)	0	(19)
Available-for-sale securities, Estimated Fair Value	$ 41,424	$ 18,621

Cash and Marketable Securitie_5

Cash and Marketable Securities - Summary of cost and estimated fair value of short-term investments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Maturing in one year or less	$ 240,561	$ 259,715
Maturing after one year through five years	52,789	0
Total	$ 293,350	$ 259,715

Basic and Diluted Net Loss Pe_2

Basic and Diluted Net Loss Per Share - Additional Information (Detail) - shares	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Stock options and RSUs outstanding (in shares)	10,370,481	8,770,775

Major Customers, Partnerships_3

Major Customers, Partnerships and Strategic Alliances - Additional Information (Detail)	Apr. 05, 2018USD ($)	Sep. 30, 2019USD ($)	May 31, 2018USD ($)	Dec. 31, 2017USD ($)milestone	May 31, 2017USD ($)	Jan. 31, 2014USD ($)program	Sep. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2019USD ($)Milestone	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)Product	Sep. 30, 2019USD ($)Product	Aug. 31, 2019USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues							$ 21,958,000		$ 23,562,000		$ 47,577,000	$ 57,615,000
Other long-term liabilities		$ 5,542,000					5,542,000			$ 1,960,000	5,542,000		$ 5,542,000	$ 5,542,000	$ 5,542,000
California Institute For Regenerative Medicine Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Funds due under the agreement			$ 8,000,000
Other long-term liabilities		5,500,000					5,500,000			1,800,000	5,500,000		5,500,000	5,500,000	5,500,000
California Institute For Regenerative Medicine Agreement | Research Grants
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues										1,700,000			5,200,000
Kite Pharma Inc
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues							8,861,000		9,028,000		26,233,000	16,544,000
Kite Pharma Inc | Collaboration Agreements
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues							$ 6,296,000		6,296,000		18,682,000	12,249,000
Kite Pharma Inc | Collaboration and License Agreement
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. 5, 2018
Milestone payments received	$ 150,000,000
Initial research term of agreement	6 years
Lease agreement, extendable lease term	2 years
Research agreement term							an option to extend the research term of the agreement for up to two additional one-year periods for a separate upfront fee of $10.0 million per year.
Separate upfront fee	$ 10,000,000
Collaborative arrangement estimated reimbursable service costs for new research plan		3,400,000
Collaborative arrangement transaction price	189,300,000
Revenues under agreement	150,000,000
Collaborative arrangement estimated reimbursable service costs	39,300,000
Deferred revenue		112,800,000					$ 112,800,000			131,500,000	112,800,000		112,800,000	112,800,000	112,800,000
Kite Pharma Inc | Collaboration and License Agreement | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received	3,010,000,000
Kite Pharma Inc | Collaboration and License Agreement | Achievement of Specified Research, Clinical Development, Regulatory and First Commercial Sale Milestones
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 | Collaboration and License Agreement | Achievement of Specified Sales-based Milestones if Annual Worldwide Net Sales of Licensed Products Reach Specified Levels
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
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments received				$ 12,000,000
Collaborative arrangement transaction price				$ 12,000,000	$ 70,000,000
Revenues under agreement					70,000,000									0
Deferred revenue		12,400,000					12,400,000			10,000,000	12,400,000		12,400,000	$ 12,400,000	12,400,000
Number of products approved | Product														0
Pfizer | Collaboration Agreements
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue reduction due to decrease in measure of proportional cumulative performance								$ 3,000,000
Revenues							468,000		394,000		$ 1,538,000	1,470,000
Pfizer | SB-525
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of milestones included in transaction price | Milestone											0
Pfizer | Royalty Revenues
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues														$ 0
Pfizer | C9ORF72
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Deferred revenue		8,300,000					8,300,000			9,800,000	$ 8,300,000		8,300,000	8,300,000	$ 8,300,000
Number of milestones included in transaction price | milestone				0
Pfizer | Maximum | SB-525
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
Milestone revenue receivable					300,000,000
Pfizer | Maximum | Other Products
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone revenue receivable					175,000,000
Pfizer | Achievement of Specified Clinical Development Intellectual Property and Regulatory Milestones | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received					208,500,000
Pfizer | Achievement of First Commercial Sale Milestones | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received					$ 475,000,000
Pfizer | Achievement of Specified Preclinical Development Clinical Development and First Commercial Sale Milestones | Maximum | C9ORF72
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received				$ 60,000,000
Pfizer | Achievement of Commercial Milestones | Maximum | C9ORF72
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received				$ 90,000,000
Pfizer SB-525 | Collaboration Agreements
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues							3,440,000		10,421,000		5,035,000	26,262,000
Sanofi
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues under agreement						$ 20,000,000
Number of products approved | Product															0
Revenues							2,754,000		2,240,000		7,763,000	11,139,000
Number of research programs | program						2
Sanofi | Collaboration Agreements
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues							940,000		$ 1,094,000		2,594,000	$ 3,432,000
Sanofi | Collaboration and License Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments received											$ 6,000,000
Collaborative arrangement transaction price						$ 75,700,000
Revenues under agreement						20,000,000
Collaborative arrangement estimated reimbursable service costs						55,700,000
Number of milestones included in transaction price | Milestone											0
Sanofi | Collaboration and License Agreement | Royalty Revenues
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues															$ 0
Sanofi | Collaboration and License Agreement | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received						276,300,000
Sanofi | Collaboration and License Agreement | Achievement Of Specified Clinical Development And Regulatory Milestones | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received						115,800,000
Sanofi | Collaboration and License Agreement | Achievement of Specified Sales Milestones | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Development and sales-based milestone payments to be received						$ 160,500,000
Sanofi | Collaboration and License Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Deferred revenue		$ 2,000,000					$ 2,000,000			$ 4,600,000	$ 2,000,000		$ 2,000,000	$ 2,000,000	$ 2,000,000
Milestone revenue receivable																$ 6,000,000

Major Customers, Partnerships_4

Major Customers, Partnerships and Strategic Alliances - Revenues Recognized under Agreement (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues	$ 21,958	$ 23,562	$ 47,577	$ 57,615
Kite Pharma Inc
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues	8,861	9,028	26,233	16,544
Kite Pharma Inc | Collaboration Agreements
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues	6,296	6,296	18,682	12,249
Kite Pharma Inc | Research Services
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues	2,565	2,732	7,551	4,295
Pfizer SB-525 | Collaboration Agreements
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues	3,440	10,421	5,035	26,262
Pfizer | Collaboration Agreements
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues	468	394	1,538	1,470
Sanofi
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues	2,754	2,240	7,763	11,139
Sanofi | Collaboration Agreements
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues	940	1,094	2,594	3,432
Sanofi | Research Services
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenues	$ 1,814	$ 1,146	$ 5,169	$ 7,707

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 4,701	$ 3,810	$ 14,091	$ 10,374
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	2,268	2,093	7,329	5,972
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 2,433	$ 1,717	$ 6,762	$ 4,402

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)ft²	Mar. 31, 2019	Sep. 30, 2019USD ($)ft²contract	Jun. 30, 2019ft²	Jan. 31, 2019ft²
Commitments And Contingencies [Line Items]
Operating lease costs | $	$ 2.6		$ 5.3
Lease option to extend			true
Variable lease expense | $	$ 0.6		$ 1.2
Cash paid for operating lease liabilities included net cash used in operating activities | $			$ 2
Operating lease, weighted-average remaining lease term	9 years 1 month 6 days		9 years 1 month 6 days
Operating lease, weighted-average discount rate	6.90%		6.90%
Richmond Lease | Office and Laboratory
Commitments And Contingencies [Line Items]
Area of space leased (in sqft)	37,900		37,900
Richmond Lease | Operating Lease One | Research and Office Space
Commitments And Contingencies [Line Items]
Area of space leased (in sqft)	7,700		7,700
Lease expiration date			Aug. 31, 2019
Valbonne Lease
Commitments And Contingencies [Line Items]
Additional property available under lease | contract			2
Valbonne Lease | Operating Lease One | Research and Office Space
Commitments And Contingencies [Line Items]
Area of space leased (in sqft)	14,036		14,036
Valbonne Lease | Operating Lease Two | Office Space
Commitments And Contingencies [Line Items]
Area of space leased (in sqft)	6,800		6,800
Lease commencement date		Apr. 1, 2019
Richmond and Valbonne Leases
Commitments And Contingencies [Line Items]
Lease option to extend			Certain of these leases also include renewal options at the election of the Company to renew or extend the lease for an additional five to ten years.
Richmond and Valbonne Leases | Minimum
Commitments And Contingencies [Line Items]
Lease agreement, extendable lease term	5 years		5 years
Richmond and Valbonne Leases | Maximum
Commitments And Contingencies [Line Items]
Lease agreement, extendable lease term	10 years		10 years
Brisbane Lease
Commitments And Contingencies [Line Items]
Area of space leased (in sqft)				52,620
Expected lease commencement period			2019-06
Tenant improvement allowance | $	$ 6.8		$ 6.8
Lease not yet commenced, tenant improvement allowance | $	$ 10.2		$ 10.2
Brisbane Lease | Office and Laboratory
Commitments And Contingencies [Line Items]
Area of space leased (in sqft)	87,700		87,700
Brisbane Lease | Office Space
Commitments And Contingencies [Line Items]
Area of space leased (in sqft)					35,080
Lease commencement period			2019-01

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Maturities of Operating Lease Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Three months ending December 31, 2019	$ 1,073
2020	6,055
2021	6,097
2022	6,165
2023	6,243
Thereafter	31,946
Total lease payments	57,579
Imputed interest	(13,976)
Total	43,603
Operating lease liabilities - current (included in Accounts payable and accrued liabilities on the Condensed Consolidated Balance Sheet)	2,994
Operating lease liabilities - long-term	40,609	$ 27,689
Total	$ 43,603

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		9 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	May 31, 2017
ATM Agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issuable and sellable under offering agreement			$ 75		$ 75
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock under public offering, net of issuance costs (in shares)	12,700,000	14,200,000	12,650	14,157
Public offering price of common stock issued (in USD per share)	$ 11.50	$ 16.25
Net proceeds from issuance of common stock, after deducting offering expenses	$ 136.3	$ 215.8

Acquisition of Sangamo Therap_3

Acquisition of Sangamo Therapeutics France S.A.S. - Additional Information (Detail) - USD ($)	Nov. 23, 2018	Oct. 01, 2018	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Jul. 20, 2018
Business Acquisition [Line Items]
Purchase of additional Sangamo France shares					$ 262,000	$ 0
Goodwill impairments					$ 0		$ 0
TxCell S.A.
Business Acquisition [Line Items]
Number of ordinary shares acquired (in shares)		13,519,036	111,000	11,528,635
Purchase of additional Sangamo France shares			$ 300,000
Purchase price per share (usd per share)		$ 2.99
TxCell S.A. | Share Purchase Agreement and Tender Offer Agreement
Business Acquisition [Line Items]
Percentage of equity interests agreed to acquire								100.00%
Number of ordinary shares acquired (in shares)	11,528,635		111,000	25,047,671
Number of free shares held by the holders (in shares)		477,000	477,000		477,000
Purchase of additional Sangamo France shares			$ 300,000
Estimated fair value liability of free shares		$ 200,000
Estimated fair value asset of free shares			$ 200,000		$ 200,000
TxCell S.A. | Share Purchase Agreement and Tender Offer Agreement | Option Pricing Method
Business Acquisition [Line Items]
Estimated fair value liability of free shares		$ 200,000		$ 200,000			$ 200,000
TxCell S.A. | Share Purchase Agreement and Tender Offer Agreement | Former Executive of TxCell
Business Acquisition [Line Items]
Number of ordinary shares acquired (in shares)			52,700
TxCell S.A. | SPA
Business Acquisition [Line Items]
Number of ordinary shares acquired (in shares)		13,519,036
TxCell S.A.
Business Acquisition [Line Items]
Noncontrolling interest ownership percentage			98.70%	98.20%	98.70%		98.20%
TxCell S.A. | Share Purchase Agreement and Tender Offer Agreement
Business Acquisition [Line Items]
Noncontrolling interest ownership percentage			98.70%	98.20%	98.70%		98.20%

Acquisition of Sangamo Therap_4

Acquisition of Sangamo Therapeutics France S.A.S. - Summary of Estimated Fair Value of Net Assets Acquired (Detail) - USD ($) $ in Thousands	Oct. 01, 2018	Sep. 30, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill		$ 38,270	$ 40,044
TxCell S.A.
Business Acquisition [Line Items]
Consideration transferred	$ 45,911
Fair value of non-controlling interest	35,829
Fair value of TxCell	81,740
Cash	4,779
Current assets	2,427
Property and equipment	1,857
IPR&D	55,019
Other assets	155
Current liabilities	(9,761)
Assumed debt liabilities	(4,933)
Deferred tax liability, net	(6,798)
Fair value of net identifiable assets acquired	42,745
Goodwill	38,995
Total fair value of net assets acquired	$ 81,740

Acquisition of Sangamo Therap_5

Acquisition of Sangamo Therapeutics France S.A.S. - Summary of Non-controlling Interest (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Noncontrolling Interest [Roll Forward]
Non-controlling interest, beginning balance			$ 739
Fair value of additional shares acquired	$ (321)		(321)
Loss attributable to non-controlling interest	(54)	$ 0	(179)	$ 0
Non-controlling interest, ending balance	$ 239		$ 239

Uncategorized Items - sgmo-2019

Label	Element	Value
Accounting Standards Update 2014-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 1,117,000
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 1,117,000