Commitments and contingencies - Operating Lease Obligations (Details) |
12 Months Ended | |
|---|---|---|
|
Dec. 31, 2017
USD ($)
vehicle
|
Dec. 31, 2016
USD ($)
|
|
| Office space and warehouse facilities | ||
| Operating Leased Assets [Line Items] | ||
| Rent expense, gross | $ 700,335 | $ 691,769 |
| Rent expense, sublease rent offset | 34,995 | 63,842 |
| Rent expense, net | 665,340 | 627,927 |
| Vehicles | ||
| Operating Leased Assets [Line Items] | ||
| Rent expense, net | $ 1,571 | $ 6,918 |
| Operating leased assets, number of assets | vehicle | 1 | |
| X | ||||||||||
- Definition Operating Leased Assets, Number of Assets No definition available.
|
| X | ||||||||||
- 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.
|
| X | ||||||||||
- Definition This element represents the payments that the lessee is obligated to make or can be required to make in connection with a property under the terms of an agreement classified as an operating lease, excluding contingent rentals and a guarantee by the lessee of the lessor's debt and the lessee's obligation to pay (apart from the rental payments) executory costs such as insurance, maintenance, and taxes. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition The total amount of sublease rental income recognized during the period that reduces the entity's rent expense incurred under operating leases. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|