Share-based compensation expenses (Schedule of Share-Based Compensation Related to Employees) (Details) (Stock Options Related to Employees [Member], USD $)	6 Months Ended
Jun. 30, 2013
Stock Options Related to Employees [Member]
Number of Shares
Outstanding, January 1, 2013	665,000
Granted
Exercised
Forfeited	100,000
Outstanding, June 30, 2013	565,000
Exercisable, June 30, 2013	275,000
Weighted Average Exercise Price
Outstanding, January 1, 2013	$ 2.81
Granted
Exercised
Forfeited	$ 1.15
Outstanding, June 30, 2013	$ 3.10
Exercisable, June 30, 2013	$ 3.24
Remaining Contractual Term in Years
Outstanding	7 years 8 months 12 days
Exercisable, June 30, 2013	7 years 7 months 28 days

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 50

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

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

-Publisher FASB

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

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No definition available.

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- Definition

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

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

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Weighted average price at which option holders acquired shares when converting their stock options into shares.

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No definition available.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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No definition available.

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Number of share options (or share units) exercised during the current period.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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