Loss per Common Share (Tables)

3 Months Ended

Mar. 31, 2019

Earnings Per Share [Abstract]

Schedule of Potential Common Shares Issuable Pursuant to Outstanding Securities Excluded from Computation of Diluted Loss per Common Share

The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted loss per common share because their inclusion would have had an anti-dilutive effect (in thousands):

	Three months ended March 31,
	2019		2018
Warrants to purchase shares of common stock		218		5,218
Convertible preferred stock		16,331		6,331
Options to purchase shares of common stock		4,005		3,288
Outstanding securities not included in    calculations		20,554		14,837