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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Related Party Transactions - Additional Information (Detail) - USD ($)		3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 29, 2016	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2015
Related Party Transaction [Line Items]
Change in fair value of derivative liability			$ 183,000		$ 211,000
Amounts expensed for services incurred		$ 14,753,000	12,378,000	$ 28,374,000	28,720,000
Research and development expense		9,998,000	7,489,000	19,474,000	17,672,000
MD Anderson License and the Research and Development Agreement Member [Member]
Related Party Transaction [Line Items]
Research and development service agreement aggregate quarterly payments				3,000,000	2,200,000
Cash resources on hand		24,200,000	27,800,000	24,200,000	27,800,000
MD Anderson License and the Research and Development Agreement Member [Member] \| Other Current Assets [Member]
Related Party Transaction [Line Items]
Cash resources on hand		19,400,000		19,400,000
MD Anderson License and the Research and Development Agreement Member [Member] \| Other Noncurrent Assets [Member]
Related Party Transaction [Line Items]
Cash resources on hand		4,800,000		4,800,000
Series 1 Preferred Stock
Related Party Transaction [Line Items]
Temporary equity, fair value		5,400,000		5,400,000
Change in fair value of derivative liability					200
License Agreement \| M.D. Anderson Cancer Center
Related Party Transaction [Line Items]
Issuance of common stock in licensing agreement (in shares)							11,722,163
Research and development expense							$ 67,300,000
Cooperative Research and Development Agreement \| M.D. Anderson Cancer Center
Related Party Transaction [Line Items]
Research and development service agreement aggregate quarterly payments					2,700,000
Research and development service agreement aggregate payments					41,900,000
Intrexon Corporation/Precigen
Related Party Transaction [Line Items]
Amounts expensed for services incurred				1,500,000	4,700,000
Amount due to related party, current		$ 1,100,000	$ 1,900,000	$ 1,100,000	$ 1,900,000
Research and development expense						$ 1,000,000
Intrexon Corporation/Precigen \| Series 1 Preferred Stock
Related Party Transaction [Line Items]
Issuance of common stock in licensing agreement (in shares)	100,000		3,734