Note payable (Details Textual)	12 Months Ended
	Dec. 31, 2017
Working Capital Loan 1 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jun. 30, 2017
Debt Instrument, Basis Spread on Variable Rate	1.00%
Working capital loan 2 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Mar. 31, 2018
Debt Instrument, Basis Spread on Variable Rate	1.04%