Income taxes - Narrative (Details) - USD ($) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Operating Loss Carryforwards [Line Items] | ||
| Decrease attributable to reduction in tax rates | $ 4,747,000 | |
| Internal Revenue Service (IRS) | ||
| Operating Loss Carryforwards [Line Items] | ||
| Operating loss carryforwards | 30,982,000 | |
| Income Tax Provision | ||
| Operating Loss Carryforwards [Line Items] | ||
| Change in valuation allowance | $ 277,000 | $ 96,754 |
| X | ||||||||||
- Definition Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit) No definition available.
|
| X | ||||||||||
- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- 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
|
| 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 | ||||||||||
- Details
|
| X | ||||||||||
- Details
|