Schedule of calculation of diluted net loss per share allocable to common stockholders (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	39,781,592	28,102,805	24,920,395
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	23,781,930	25,030,234	20,872,824
Warrant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	6,534,687	1,832,571	3,007,571
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	2,403,951
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	7,061,024	1,240,000	1,040,000