Summary of Significant Accounting Policies - Net loss per share (Details)	12 Months Ended
	Dec. 31, 2019 shares
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	30,646,217
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	27,093,334
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,278,324
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	274,559