Stockholders' deficit - Warrants (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Ending Balance, warrants	97,499,908
Ending Balance, warrants exercise price	$ 0.091
Minimum [Member]
Beginning balance, warrants exercise price	0.03	$ 0.03
Warrants granted, price	0.10	0.03
Ending Balance, warrants exercise price	0.03	0.03
Maximum [Member]
Beginning balance, warrants exercise price	0.0033	0.0033
Warrants granted, price	0.12	0.10
Ending Balance, warrants exercise price	$ 0.12	$ 0.0033
Warrants
Beginning balance, warrants	49,504,075	19,637,409
Warrants Granted, shares	48,295,833	29,866,666
Warrants Cancelled, shares	(300,000)
Ending Balance, warrants	97,499,908	49,504,075
Beginning balance, warrants exercise price	$ 0.069	$ 0.030
Warrants granted, price	0.113	0.095
Warrants cancelled, price	0.003
Ending Balance, warrants exercise price	$ 0.091	$ 0.069