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Equity and Stock-based Compensation - Schedule of Warrants to Purchase Shares of Common Stock (Detail)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Class Of Warrant Or Right [Line Items]
Number of Shares	4,430
Year of Issuance 2000 [Member]
Class Of Warrant Or Right [Line Items]
Year of Issuance	2000
Number of Shares	4,430
Exercise Price per Share | $ / shares	$ 15.00
Reason for Issuance	Issued in connection with lease agreement
Expiration Date	Five years after initial public offering or upon merger or sale of the Company’s assets, whichever occurs first

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- Definition

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- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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- Definition

Description of the purpose of issuing warrants to nonemployees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5047-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 50
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68057994&loc=d3e25284-112666

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