Share capital (Details) - Stock Option [Member]	9 Months Ended
	Sep. 30, 2018 $ / shares shares
Disclosure of financial assets [line items]
Number of outstanding options, Beginning | shares	5,710,000
Expired / Cancelled | shares
Not vested | shares	30,000
Number of outstanding options, Ending | shares	5,740,000
Options exercisable | shares	5,710,000
Weighted average exercise price, Beginning | $ / shares	$ 1.75
Expired / Cancelled | $ / shares
Not vested | $ / shares	3.43
Weighted average exercise price, Ending | $ / shares	1.76
Options exercisable | $ / shares	$ 1.75
Weighted average remaining contractual life (in years), Beginning	7 years 4 months 20 days
Weighted average remaining contractual life (in years), Not vested	3 years 10 months 6 days
Weighted average remaining contractual life (in years), Ending	6 years 7 months 14 days
Weighted average remaining contractual life options exercisable (in years)	6 years 7 months 20 days