Significant assumptions used for warrants (Details)	12 Months Ended
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average term	4 years 3 months
Volatility	101.00%
Risk-free interest rate	0.72%

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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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- Definition

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

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- Definition

Weighted average expected volatility of stock price.

+ References

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