Represents the number of long-lived assets determined to be impaired.

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- Definition

Represents the number of milestones achieved during the period.

+ References

No definition available.

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- Definition

Period of time over which the up-front payment received was recognized as revenue.

+ References

No definition available.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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- Definition

Amount of assets held-for-sale that are not part of a disposal group.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 15
-Paragraph 4
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=77912953&loc=d3e400-110220

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- Definition

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.

+ References

No definition available.

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- References

No definition available.

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- Definition

Fair value of financial and nonfinancial obligations.

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- Definition

Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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No definition available.

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- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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- References

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- Definition

The amount of consideration recognized during the period for the milestone or milestones.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 28
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=68058744&loc=SL6892177-166501

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- References

No definition available.

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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Summary of Significant Accounting Policies (Detail)	1 Months Ended	12 Months Ended		24 Months Ended	27 Months Ended
Summary of Significant Accounting Policies (Detail)	Aug. 31, 2015 USD ($)	Dec. 31, 2017 USD ($) segment item	Dec. 31, 2016 USD ($) item	Dec. 31, 2017 USD ($) item	Dec. 31, 2013
Fair Value Measurements
Number Of Operating Segments \| segment		1
Assets measured at fair value levels 2 or 3		$ 0	$ 0	$ 0
Liabilities measured at fair value levels 2 or 3		0	0	0
Carrying value of cash held in money market fund		$ 121,900,000	$ 38,000,000	121,900,000
Impairment of Long-Lived Assets
Number of long-lived assets determined to be impaired \| item		0	0
Assets held for sale		$ 0	$ 0	$ 0
Maximum
Share-based Compensation
Expected term		10 years
Pfizer \| License Agreement
Revenue Recognition
Milestone revenue	$ 20,000,000	$ 0	$ 0
Number of milestones met \| item				0
Pfizer \| License Agreement \| Up-Front Payment Arrangement
Revenue Recognition
Recognition period of up-front payment					1 year 6 months