Income taxes (Details Textual) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Deferred Tax Assets, Valuation Allowance | $ 0 | $ 11,997,000 | |
| Operating Loss Carryforwards | 21,974,000 | ||
| Operating Loss Carry forwards Subject To Limitation By Irs Per Year | 908,000 | ||
| Operating Loss Carryforwards Subject To Limitation By Irs | 1,257,000 | ||
| Income Tax Expense (Benefit) | (11,172,000) | $ 0 | $ 0 |
| Taxes, Other | $ 75,000 | ||