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Income taxes - Narrative (Details) (USD $)
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12 Months Ended |
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Dec. 31, 2012
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| Operating Loss Carryforwards [Line Items] | |
| Increase In Valuation Allowance | $ 496,000 |
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Internal Revenue Service (IRS)
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| Operating Loss Carryforwards [Line Items] | |
| Operating Loss Carryforwards | 8,500,000 |
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Internal Revenue Service (IRS) | Subsidiary
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| Operating Loss Carryforwards [Line Items] | |
| Operating Loss Carryforwards | $ 1,900,000 |
| X | ||||||||||
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- Definition
Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
The amount of the change in the period in the valuation allowance for a specified deferred tax asset. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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