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Fair Value Measurements - Summary of Issuances, Changes in Fair Value and Reclassifications of Level 3 Financial Instruments (Detail) - Fair Value Measured Using - (Level 3) [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	$ 34,984
Exercise of warrants	(127)
Conversion of JGB debt to common stock (Note 10)	(12,066)
Reclassification to equity (Note 2)	(6,550)
Change in estimated fair value	(1,178)
Ending Balance	15,063
Common Stock Warrant Liability [Member]
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	18,712
Exercise of warrants	(127)
Conversion of JGB debt to common stock (Note 10)	0
Reclassification to equity (Note 2)	(6,550)
Change in estimated fair value	1,212
Ending Balance	13,247
Contingent Consideration Liability [Member]
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	1,672
Exercise of warrants	0
Conversion of JGB debt to common stock (Note 10)	0
Reclassification to equity (Note 2)	0
Change in estimated fair value	144
Ending Balance	1,816
Derivative Liability [Member]
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	14,600
Exercise of warrants	0
Conversion of JGB debt to common stock (Note 10)	(12,066)
Reclassification to equity (Note 2)	0
Change in estimated fair value	(2,534)
Ending Balance	$ 0

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- Definition

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+ References

No definition available.

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- Definition

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+ References

No definition available.

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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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- Definition

Amount of gain (loss) recognized on the income statement for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ 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 (c)(1)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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- Definition

Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ 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 (c)(2)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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- Definition

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ 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 (c)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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