Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2018

Stockholders' Equity [Abstract]

Outstanding Common Stock Warrants

Outstanding common stock warrants at December 31, 2018 consist of the following:

Issue Date	Expiration Date	Total Warrants		Exercise Price
October 31, 2013*	April 30, 2019		137,143	$	3.75
February 5, 2014*	February 5, 2019		265,947	$	3.75
July 24, 2014	July 24, 2019		1,239,769	$	3.75 - $ 12.25
June 22, 2015	June 22, 2020		600,000	$	3.75
December 30, 2015	December 30, 2020		130,089	$	5.65
January 29, 2016	January 29, 2021		19,812	$	5.30
			2,392,760

*These warrants are classified as liabilities (See Note 13, Warrants).