| Outstanding warrants (Details) (USD $) | 0 Months Ended | |||
|---|---|---|---|---|
| Dec. 31, 2012 | Oct. 16, 2013
 One Group [Member] | Dec. 31, 2012
 Minimum [Member] | Dec. 31, 2012
 Maximum [Member] | |
| Class of Warrant or Right [Line Items] | ||||
| Outstanding warrants to purchase membership units | 62,280 | |||
| Number of shares exchanged for warrants exercised | 5,750,000 | |||
| Exercise price of warrants | 5.00 | 22.94 | 32.00 | |
| Merger exchange ratio | 8.09 to one | |||
| Minimum price per share per agreement | $ 6.25 | |||
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- Definition Merger exchange ratio. No definition available. 
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- Definition The minimum price per share required per agreement. No definition available. 
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- Definition Exercise price per share or per unit of warrants or rights outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
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- Definition 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. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Number of warrants or rights outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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