Warrants - Warrants outstanding and exercisable (Details) - shares	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Warrant Activity
Warrants outstanding, beginning balance	19,421,892	34,682
Issuances		20,637,761
Exercises	(1,798,962)	(1,250,000)
Expirations and cancelations		(551)
Warrants outstanding, ending balance	17,622,930	19,421,892