Summary of significant accounting policies - Concentration of Credit Risk (Details) |
12 Months Ended | |
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Dec. 31, 2016
USD ($)
customer
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Dec. 31, 2015
USD ($)
customer
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| Concentration Risk [Line Items] | ||
| Cash, FDIC Insured Amount | $ | $ 250,000 | |
| Cash, Uninsured Amount | $ | $ 3,471,765 | $ 5,329,528 |
| Customer concentration risk | Revenues | ||
| Concentration Risk [Line Items] | ||
| Number of customer representing more than 10% of revenues or trade accounts receivable | 0 | 0 |
| Number of customers | 396 | |
| Customer concentration risk | Trade accounts receivable | ||
| Concentration Risk [Line Items] | ||
| Number of customer representing more than 10% of revenues or trade accounts receivable | 1 | |
| Concentration risk, percentage | 15.00% | 16.00% |
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- Definition Concentration Risk, Number of Significant Customers No definition available.
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- Definition Credit Risk, Number of Customers No definition available.
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- Definition The amount of cash deposited in financial institutions as of the balance sheet date that is insured by the Federal Deposit Insurance Corporation. No definition available.
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- Definition The amount of cash as of the balance sheet date that is not insured by the Federal Deposit Insurance Corporation. No definition available.
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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. No definition available.
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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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