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