Fair value measurements (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2016	Dec. 31, 2015
Fair value measurements
Derivative liability-related party		$ 488
Company's ending stock price (in dollars per share)	$ 0.76	$ 0.20
Company's stock volatility (as a percent)	110.00%	85.00%
Applicable risk free interest rate (as a percent)	0.87%	1.48%
Warrant Liability
Changes in level 3
Beginning Balance	$ 210
Change in estimated fair value	2,821
Ending Balance	3,031	$ 210
Derivative Liability
Changes in level 3
Beginning Balance	488
Conversion of Sentient Loan	(488)
Ending Balance		488
Recurring
Fair value measurements
Cash and cash equivalents	3,415	4,077
Trade accounts receivable	506	546
Short-term investments	456	72
Assets	4,377	4,695
Warrant liability	3,031	210
Derivative liability-related party		488
Liabilities	3,031	698
Recurring \| Level 1
Fair value measurements
Cash and cash equivalents	3,415	4,077
Trade accounts receivable	506	546
Short-term investments	456	72
Assets	4,377	4,695
Recurring \| Level 3
Fair value measurements
Warrant liability	3,031	210
Derivative liability-related party		488
Liabilities	3,031	$ 698
Non-recurring
Fair value measurements
Fair value measurements	$ 0

Represents the fair value portion of warrants liability recognized by the entity.

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- Definition

Fair value portion of amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 2
-Subparagraph (a)
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- Definition

Fair value portion 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Risk-free interest rate assumption used in valuing an instrument.

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-Publisher FASB
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-SubTopic 10
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of increase (decrease) 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

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-Publisher FASB
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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

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-Publisher FASB
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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.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

Fair value of asset after deduction of liability.

+ References

No definition available.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Trading Securities
-URI http://asc.fasb.org/extlink&oid=6526789

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-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 1
-Subparagraph a, f, g
-Article 7

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Fair value of financial and nonfinancial obligations.

+ References

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- Definition

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

+ References

No definition available.

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