Recent accounting pronouncements Recent accounting pronouncements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred tax asset	$ 7,493,469	$ 10,346,505
Adjustments for New Accounting Pronouncement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred tax asset			$ 37,000,000
Deferred tax asset valuation allowance			$ 37,000,000
Other Assets | Accounting Standards Update 2015-03
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance cost	(6,237)	(6,237)
Current Notes Payable | Accounting Standards Update 2015-03
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance cost	$ 6,237	$ 6,237