Net loss Per Share - Anti-dilutive shares (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,509,335	4,237,648
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,893,201	2,610,078
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,616,134	1,607,570
Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	20,000