Warrants - Schedule of Warrants to Purchase Common Stock Outstanding (Detail)	9 Months Ended
Sep. 30, 2018 $ / shares shares
Warrants Issued September 2016 [Member]
Class of Warrant or Right [Line Items]
Issued	2016-09
Warrants Outstanding \| shares	13,466,667
Exercise Price \| $ / shares	$ 2.25
Expiration	2021-11
Warrants Issued March 2015 [Member]
Class of Warrant or Right [Line Items]
Issued	2015-03
Warrants Outstanding \| shares	3,699
Exercise Price \| $ / shares	$ 9.75
Expiration	2025-03
Warrants Issued July 2014 [Member]
Class of Warrant or Right [Line Items]
Issued	2014-07
Warrants Outstanding \| shares	6,566
Exercise Price \| $ / shares	$ 7.99
Expiration	2024-07
Warrants Issued July 2012 [Member]
Class of Warrant or Right [Line Items]
Issued	2012-07
Warrants Outstanding \| shares	52,046
Exercise Price \| $ / shares	$ 0.01
Expiration	2022-07

Class of warrant or right warrant expiration month and year.

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- Definition

Class of warrant or right warrant issued month and y.ear

+ References

No definition available.

+ Details

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

+ Details

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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.

+ Details

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- Definition

Number of warrants or rights outstanding.

+ References

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

+ Details

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