Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
Dec. 31, 2016 USD ($) Segment
Summary Of Significant Accounting Policies [Line Items]
Accretion amount recognized	$ 0
Percentage of likelihood of realization required to record tax benefit	50.00%
Contractual obligation	$ 0
Number of reportable segment \| Segment	1
Convertible Preferred Stock (Series B, Series A-2, Series A-1, Junior and Founder) [Member]
Summary Of Significant Accounting Policies [Line Items]
Loss to participating securities	$ 0

Percentage of likelihood of realization needed in order for the company to record a tax benefit.

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- Definition

Summary Of Significant Accounting Policies [Line Items]

+ References

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- Definition

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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- Definition

Amount of earnings (loss) distributed and earnings (loss) allocated to participating securities for the diluted earnings (loss) per share or per unit calculation under the two-class method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64863997&loc=SL5780133-109256

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- Definition

Value of accretion of temporary equity during the period due to unpaid interest.

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