Expiration date of warrants held.

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Warrants issued to purchase common stock.

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Fair value of stock (or other type of equity) granted during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP).

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The number of exercisable share warrants that may be converted as of the balance sheet date.

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As of the balance sheet date, the number of warrants into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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Per share amount of warrant.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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- Definition

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

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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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Aggregate number of common shares reserved for future issuance.

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Unrecognized cost of unvested options awarded to employees as compensation.

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

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The cash inflow from the additional capital contribution to the entity.

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Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

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The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

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No definition available.

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Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

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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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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Number of new stock issued during the period.

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Fair value portion of warrants not settleable in cash classified as equity.

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Stock-Based Compensation and Warrants (Details Textual) - USD ($)		1 Months Ended			12 Months Ended
	Oct. 10, 2014	Nov. 18, 2016	Oct. 25, 2012	Mar. 20, 2007	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 07, 2017	Aug. 25, 2016	May 15, 2015	Oct. 22, 2013	Nov. 02, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options					$ 2,900,000
Proceeds from Issuance of Common Stock		$ 300,000			0	$ 25,000,000	$ 46,000,000
Change in fair value of warrant liabilities					(10,738,000)	(11,412,000)	3,811,000
Proceeds from Stock Options Exercised					166,000	814,000	$ 41,000
IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of Stock, Price Per Share		$ 1.00
Change in fair value of warrant liabilities					9,000,000	3,000,000
Stock Issued During Period, Shares, New Issues		25,000,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		50,000,000
Warrants Not Settleable in Cash, Fair Value Disclosure		$ 15,700,000			$ 3,700,000	$ 12,700,000
Series A Warrants [Member] \| IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 1.43
Series B Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Investment Warrants Expiration Date		Dec. 31, 2017			Dec. 31, 2017
Series B Warrants [Member] \| IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Investment Warrants Expiration Date		Dec. 31, 2017
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 1.72
Warrant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of Warrants to Purchase of Common Stock			635,855
Warrants Exercise Price Per Share			$ 1.60
Employees And Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross					3,159,177	3,861,425	3,781,666
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value					$ 1,800,000	$ 3,100,000	$ 8,000,000
Employee [Member] \| General and Administrative Expenses and Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense					3,000,000	3,400,000	2,300,000
Consultant [Member] \| General and Administrative Expenses and Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense					$ 434,000	603,000	$ 888,000
2007 Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number				2,500,000	712,258
2007 Stock Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross				250,000
2010 Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number					11,851,840							3,000,000
2010 Stock Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance								17,500,000	14,000,000	8,000,000	6,000,000
2010 Stock Plan [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance								8,000,000	8,000,000	6,000,000	3,000,000
Stock Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of Warrants to Purchase of Common Stock	0.5
Share-based Compensation Arrangement by Share-based Payment Award, Warrants, Exercisable Number	7,029,808
Share-based Compensation Arrangement by Share-based Payment Award, Warrants, Vested and Expected to Vest Outstanding, Number	1.75
Sale of Stock, Number of Shares Issued in Transaction	14,059,616
Sale of Stock, Price Per Share	$ 1.47
Proceeds from Issuance of Common Stock	$ 19,100,000
Change in fair value of warrant liabilities	$ 7,400,000				$ 1,700,000	8,500,000
Warrants Not Settleable in Cash, Fair Value Disclosure					$ 416,000	$ 2,100,000