Warrants - Warrants outstanding and exercisable (Details) - shares	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Warrants
Warrants outstanding, beginning balance	19,421,892	34,682
Issuances	8,771,632	20,637,761
Exercises	(11,202,129)	(1,250,000)
Expirations and cancelations		(551)
Warrants outstanding, ending balance	16,991,395	19,421,892