Amount of expense (income) related to adjustment to fair value of warrant liability.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section 25
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=6939902&loc=d3e20148-110875

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

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Agreed upon price for the exchange of the underlying asset.

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

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Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

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Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

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Risk-free interest rate assumption used in valuing an instrument.

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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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Price of a single share of a number of saleable stocks of a company.

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Stock Options and Warrants - Warrants Issued in Connection with October 2014 Financing - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Nov. 25, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Change in fair value of warrant liability	$ 2,032,000	$ 2,630,000
Placement Agent Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing price of common stock	$ 1.75
Warrant exercise price	$ 1.75		$ 1.75
Stock price volatility	101.90%
Options and warrant expected term	3 years 15 days
Dividend rate	0.00%
Placement Agent Warrants [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing price of common stock	$ 1.75
Placement Agent Warrants [Member] \| U.S. Treasury Notes [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	1.50%
October 2014 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Change in fair value of warrant liability	$ 2,000