Commitments and Contingencies - Additional Information (Detail) $ in Thousands					1 Months Ended				12 Months Ended				32 Months Ended
	Oct. 05, 2018 USD ($)	Jan. 13, 2015 USD ($)	May 07, 2011 USD ($)	Mar. 07, 2011 USD ($)	Jul. 31, 2015 USD ($)	Dec. 31, 2012	Dec. 31, 2011	Aug. 24, 2004 Patent	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2017 USD ($)	Feb. 28, 2019 USD ($)	Jan. 30, 2018 USD ($) ft²	Mar. 31, 2016 USD ($)	Dec. 31, 2014 USD ($) shares
Commitments and Contingencies Disclosure [Line Items]
Operating lease expiration month and year						2018-10
Total rent expense									$ 700	$ 700	$ 300		$ 40
Deferred rent - current portion									13	141			141
Deferred rent-non-current portion									4	1			1
Deferred rent liability net									17	142			142
Research and development expense									34,134	$ 45,084	157,791
Research and development arrangement Terms										Pursuant to the Research and Development Agreement, the Company, Intrexon (now Precigen) and MD Anderson formed a joint steering committee that will oversee and manage the new and ongoing research programs. As provided under the MD Anderson License, the Company provided funding for research and development activities in support of the research programs under the Research and Development Agreement for a period of three years and in an amount of no less than $15.0 million and no greater than $20.0 million per year.
Cash balance									61,729	$ 70,946	$ 81,053		$ 70,946
Agreement commencement date										2015-05
MD Anderson License and the Research and Development Agreement Member [Member]
Commitments and Contingencies Disclosure [Line Items]
Research and development service agreement aggregate quarterly payments									2,700	$ 13,000
Cash resources on hand									27,800
CRADA Agreement [Member]
Commitments and Contingencies Disclosure [Line Items]
Obligations due under contract									2,500
Quarterly payments under contract									625
Total Payments									$ 2,500
Gorilla IL12 Products [Member] | Parent [Member]
Commitments and Contingencies Disclosure [Line Items]
Percentage of development costs	80.00%
Percentage of operating profits	80.00%
CAR Products [Member]
Commitments and Contingencies Disclosure [Line Items]
Amount of royalties receivable	$ 50,000
The University of Texas MD Anderson Cancer Center and The Texas A & M University System
Commitments and Contingencies Disclosure [Line Items]
Milestone maximum payment																	$ 4,500
Number of products | Patent								2
Options to purchase common stock | shares									50,222
Shares vested | shares																	37,666
The University of Texas MD Anderson Cancer Center and The Texas A & M University System | Research and Development Expense
Commitments and Contingencies Disclosure [Line Items]
Issuance of common stock in a license agreement									$ 87
The University of Texas MD Anderson Cancer Center and The Texas A & M University System | Upon enrollment of the first patient in a multi-center pivotal clinical trial
Commitments and Contingencies Disclosure [Line Items]
Shares vested | shares																	12,556
Solasia
Commitments and Contingencies Disclosure [Line Items]
Upfront payment received			$ 5,000	$ 5,000
Milestone payment received																$ 1,000
Milestone Payments Payable																$ 1,000
Solasia | Development-based milestones
Commitments and Contingencies Disclosure [Line Items]
Expected Additional milestone payments to be received									32,500
Solasia | Sales-based milestones
Commitments and Contingencies Disclosure [Line Items]
Expected Additional milestone payments to be received									$ 53,500
Baxter Healthcare Corporation | Upon the successful U.S. IND application for indibulin
Commitments and Contingencies Disclosure [Line Items]
Installment payments										250
ARES Trading License
Commitments and Contingencies Disclosure [Line Items]
Research and development expense										$ 1,600
Agreement termination, notice period									90 days
Subsequent Event | CRADA Agreement [Member]
Commitments and Contingencies Disclosure [Line Items]
Additional commitment														$ 5,000
Prepaid Expenses and Other Current Assets | MD Anderson License
Commitments and Contingencies Disclosure [Line Items]
Cash balance									$ 18,400
Other Noncurrent Assets | MD Anderson License
Commitments and Contingencies Disclosure [Line Items]
Cash balance									9,400
Intrexon Corporation
Commitments and Contingencies Disclosure [Line Items]
Licensing fee					$ 115,000
Research and development expense									$ 1,000
Milestone payment receivable period									2 years
Upfront payment received					$ 57,500
Percentage of upfront fee Payable					50.00%
Annual Licensing fee	100
Reimbursement of historical costs	1,000
Expected additional milestones payable	52,500
Intrexon Corporation | License [Member]
Commitments and Contingencies Disclosure [Line Items]
Annual Licensing fee	$ 100
Intrexon Corporation | Gorilla IL12 Products [Member]
Commitments and Contingencies Disclosure [Line Items]
Percentage of development costs	20.00%
Percentage of operating profits	20.00%
Intrexon Corporation | T-cell receptor
Commitments and Contingencies Disclosure [Line Items]
Maximum royalty amount	$ 100,000
Portion of income payable to related party	20.00%
Minimum | MD Anderson License and the Research and Development Agreement Member [Member]
Commitments and Contingencies Disclosure [Line Items]
Research and development expense		$ 15,000
Maximum | MD Anderson License and the Research and Development Agreement Member [Member]
Commitments and Contingencies Disclosure [Line Items]
Research and development expense		$ 20,000
New York, NY
Commitments and Contingencies Disclosure [Line Items]
Letter of credit									$ 388
Loss on sublease												$ 729
Remaining contractual obligation												2,300
Sublease revenue from subtenant												$ 1,600
Boston, MA
Commitments and Contingencies Disclosure [Line Items]
Operating lease expiration month and year							2016-08
Security deposits									$ 128
Sublease term amendment									Aug. 31, 2021
Houston, TX
Commitments and Contingencies Disclosure [Line Items]
Operating lease area | ft²															210
Operating Leases Future Minimum Monthly Payment Due Through Year 2021															$ 1