Common Stock Warrants Outstanding (Tables)

9 Months Ended

Sep. 30, 2018

Equity Classified Warrants [Abstract]

Summary of Equity-Classified Common Stock Warrant Activity

A summary of equity-classified common stock warrant activity for the nine months ended September 30, 2018 is as follows:

					Average
			Weighted		Remaining
	Number of		Average Exercise		Contractual
	Shares		Price Per Share		Term in Years
Outstanding at December 31, 2017		288,196	$	78.86		4.0
Issued		4,406,731	$	3.95
Exercised		—		—
Expired		—		—
Outstanding at September 30, 2018		4,814,927	$	5.44		4.7