Share-based compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-based Compensation, Activity [Table Text Block]

Options Granted to Employees

	Number of Shares			Weighted Average Exercise Price		Remaining Contractual Term in Years
				$
Outstanding, January 1, 2017		555,392			2.70		7.39
Granted		665,000			4.59		-
Exercised		(294,667	)		3.26		-
Forfeited		(3,619	)		2.63		-
Canceled		(7,064	)		2.63		-
Outstanding, December 31, 2017		915,042			4.07		8.34
Exercisable, December 31, 2017		130,042			2.80		5.74

	Number of Shares			Weighted Average Exercise Price		Remaining Contractual Term in Years
				$
Outstanding, January 1, 2018		915,042			4.07		8.34
Granted		40,500			4.10		-
Forfeited		(106,312	)		4.44		-
Canceled		(25,382	)		4.63		-
Outstanding, December 31, 2018		823,848			4.01		7.50
Exercisable, December 31, 2018		392,350			3.73		7.31

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The fair value of each stock option grant was estimated on the date of grant using the Black-Scholes option pricing model under the following assumptions:

	For the years ended December 31,
	2018			2017
Dividend yield		-			-
Risk-free interest rate		2.49	%		2%-2.06%
Expected term (in years)		6.05			6-6.05
Volatility		75.15	%		76.16%-76.74%