Settlement of a Related Party Relationship - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 05, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Transaction advisory costs recognized as expense						$ 2,000
Research and development expense		$ 8,641	$ 8,263	$ 28,115	$ 25,935
Accrued expenses		$ 9,573		$ 9,573		8,763
Gorilla IL-12 Products
Percentage of development cost shared by other party	80.00%
Percentage of operating profit shared by other party	80.00%
Intrexon Corporation/Precigen
Annual Licensing fee	$ 100
Reimbursement of historical costs	1,000
Preferred stock, contract liability, derivative liability	163,300
Increase in accumulated deficit	49,500
Related party transaction, amounts of transaction	212,800
Research and development expense						$ 1,000
Additional milestone payment for exclusively licensed program to be paid	52,500
Maximum Royalty payable	$ 100,000
Percentage of sublicensing income	20.00%
Royalty payment to be received	$ 50,000
Intrexon Corporation/Precigen | Gorilla IL-12 Products
Percentage of development cost shared by other party	20.00%
Percentage of operating profit shared by other party	20.00%
Third Party Vendor
Transaction advisory costs recognized as expense	$ 7,400
Series 1 Preferred Stock [Member]
Transaction advisory costs recognized as expense	5,400
Series 1 Preferred Stock [Member] | Intrexon Corporation/Precigen
Consideration transferred	207,300
Preferred Stock Redemption Discount	$ 5,400