Nature of Business, Basis of Presentation and Liquidity - Liquidity and going concern (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Liquidity and going concern
Accumulated deficit	$ 123,804		$ 123,804		$ 100,670
Net loss	6,815	$ 7,277	23,134	$ 19,901
Decrease in cash and cash equivalents	2,968
Cash and cash equivalents	$ 14,203		$ 14,203		$ 793
Minimum period to fund Operating expense			1 year

No definition available.

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Minimum period for Research and Development tax incentive to fund operating expense, 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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No definition available.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Amount of increase (decrease) in cash and cash equivalents. Cash and cash equivalents are the amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Includes effect from exchange rate changes.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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