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

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The related party's percentage of fully diluted equity participation in the entity.

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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 deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

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Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

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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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-Subparagraph (SX 210.5-03.4)
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Revenue from multiple-deliverable arrangements that include licensing fees and services revenue. Licensing revenue is consideration received from another party for the right to use, but not own, certain of the entity's intangible assets. Licensing arrangements include, but are not limited to, rights to use a patent, copyright, technology, manufacturing process, software or trademark. Licensing fees are generally, but not always, fixed as to amount and not dependent upon the revenue generated by the licensing party. An entity may receive licensing fees for licenses that also generate royalty payments to the entity. Services revenue may be derived by providing other, nonspecified, services during the reporting period.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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The number of preferred units issued.

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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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No definition available.

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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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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, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 31, 2015
Related Party Transaction [Line Items]
Research and development expense related to license and service agreements with related party			$ 21,170	$ 17,481	$ 15,565	$ 13,431	$ 11,331	$ 7,861	$ 7,423	$ 5,225	$ 67,647	$ 31,840	$ 11,170
General and administrative expenses			10,213	5,711	6,369	5,732	5,118	4,705	3,729	3,246	28,025	16,798	8,283
Collaboration revenue			$ 6,668	$ 7,317	$ 5,917	$ 6,215	5,627	$ 4,869	$ 4,206	$ 1,777	$ 26,117	$ 16,479	$ 6,044
Class A-2 Preferred Units [Member]
Related Party Transaction [Line Items]
Common stock, shares acquired													1,333,333
Caribou [Member]
Related Party Transaction [Line Items]
Junior preferred units issued		8,110,599
Percentage of related party obligation		30.00%									30.00%	30.00%	30.00%
Percentage of shares owned			10.70%								10.70%
Research and development expense related to license and service agreements with related party												$ 1,300	$ 1,500
Current obligations related to license and service agreements with related party													600
General and administrative expenses											$ 500	900	1,100
Novartis [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Percentage of shares owned			9.70%								9.70%
Common stock, shares acquired	277,777
Collaboration revenue											$ 9,300	7,800	$ 6,000
Accounts receivable			$ 6,000				6,000				6,000	6,000
Deferred revenue			$ 11,200				$ 11,600				$ 11,200	$ 11,600
Novartis [Member] \| Class A-1 Preferred Units [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Junior preferred units issued		4,761,905
Novartis [Member] \| Class A-2 Preferred Units [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Junior preferred units issued		2,666,666
Novartis [Member] \| Series B Preferred Stock [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Preferred stock, shares acquired														761,905