The entity's obligation to fund intellectual property costs of the related party.

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Amount of receivables arising from transactions with related parties due within one year or the normal operating cycle, if longer.

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

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The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Number of new stock issued during the period.

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Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended								12 Months Ended
	May 31, 2016	Jul. 31, 2014	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
General and administrative expenses			$ 8,708	$ 8,270	$ 7,805	$ 7,406	$ 10,213	$ 5,711	$ 6,369	$ 5,732	$ 32,189	$ 28,025	$ 16,798
Research and development expense related to license and service agreements with related party			19,918	23,237	23,467	22,493	21,170	17,481	15,565	13,431	89,115	67,647	31,840
Collaboration revenue			7,880	$ 7,408	$ 7,677	$ 7,469	6,668	$ 7,317	$ 5,917	$ 6,215	30,434	26,117	$ 16,479
Deferred revenue			$ 55,932				59,868				$ 55,932	$ 59,868
Caribou [Member]
Related Party Transaction [Line Items]
Percentage of related party obligation		30.00%									30.00%	30.00%	30.00%
Percentage of shares owned			5.50%								5.50%
General and administrative expenses											$ 900	$ 500	$ 900
Research and development expense related to license and service agreements with related party													1,300
Novartis [Member] \| Collaborative Arrangement
Related Party Transaction [Line Items]
Percentage of shares owned			9.60%								9.60%
Common stock, shares acquired	277,777
Collaboration revenue											$ 10,300	9,300	$ 7,800
Accounts receivable			$ 6,000				6,000				6,000	6,000
Deferred revenue			$ 14,500				$ 11,200				$ 14,500	$ 11,200