Commitments and contingencies - Additional Information (Details) - USD ($) |
9 Months Ended | |
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Sep. 30, 2015 |
Dec. 31, 2014 |
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| Guarantor Obligations [Line Items] | ||
| Short-term investments, restricted | $ 294,728 | $ 585,702 |
| Revolving Credit Facility [Member] | ||
| Guarantor Obligations [Line Items] | ||
| Letters of Credit Outstanding, Amount | 583,073 | |
| Letter of credit, increase from accrued interest | $ 2,629 |
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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 The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. No definition available.
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- Definition Increase for accrued, but unpaid interest on the credit facility for the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This element represents the current portion of investments which are not defined as or included in marketable (debt, equity, or other) securities that are pledged or subject to withdrawal restrictions. No definition available.
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- Details
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