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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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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