Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Summary of Significant Weighted Average Assumptions Used for Estimating Fair Value Under Stock Option Plans

The following are the significant weighted average assumptions used for estimating the fair value under our stock option plans:

	2019		2018			2017
Per share fair value at grant date		—	$	1.45			—
Risk free interest rate		—		3.0	%		—
Expected volatility		—		224.	%		—
Dividend yield		—		0	%		—
Expected life in years		—		4.0			—

Summary of Stock Option Transactions under Stock Option Plan

Option activity during the three years ended December 31, 2019 was as follows:

	Number of Shares			Weighted Average Exercise Price
Outstanding at December 31, 2016		13,116		$	360.30
Granted		—			—
Canceled		(503	)		45.10
Exercised		—			—
Outstanding at December 31, 2017		12,613			370.30
Granted		128,000			1.92
Canceled		(290	)		4,723.90
Exercised		—			—
Outstanding at December 31, 2018		140,323			25.29
Granted		—			—
Canceled		(3,067	)		29.11
Exercised		—			—
Outstanding at December 31, 2019		137,256		$	25.20

Summary of Currently Outstanding and Exercisable Stock Options

The following table summarizes information concerning currently outstanding and exercisable stock options at December 31, 2019:

								Exercisable
Range of Exercise Prices		Number Outstanding		Weighted Average Remaining Contractual Life in Years		Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
	$1.92 – $1.92		125,500		8.8	$	1.92		62,750	$	1.92
	33.00 – 33.00		4,867		5.9		33.00		4,867		33.00
	318.00 – 318.00		6,217		3.9		318.00		6,217		318.00
	378.00 – 2,844.00		610		3.1		1,289.50		610		1,289.50
	$3,150.00 – $5,148.00		62		0.5		4,722.63		62		4,722.63
			137,256		8.4	$	25.20		74,507	$	44.81

Summary of Weighted-Average Grant Date Fair Value of Restricted Stock Awards

The weighted-average grant date fair value of our restricted stock awards, their total fair value and the fair value of all shares that have vested during each of the past three years is as follows:

	Year ended December 31
	2019		2018		2017
Weight-average grant date fair value		—		—	$	10.70
Fair value of restricted stock awards granted		—		—	$	48,000
Fair value of restricted stock awards vested		—		—	$	23,000

Summary of Outstanding Warrants

The following is a summary of outstanding warrants at December 31, 2019:

	Common Shares
	Total		Currently Exercisable		Price per Share		Expiration Date
Warrants related to February 2015 agreement		306		306	$	450.45		February 13, 2020
Warrants related to March 2015 financing		10,209		10,209	$	244.88		September 24, 2020
Warrants related to March 2015 financing		1,021		1,021	$	306.09		March 20, 2020
Warrants related to October 2015 financing		135,517		135,517	$	60.00		October 14, 2020
Warrants related to October 2015 financing		9,034		9,034	$	65.63		October 14, 2020
Warrants related to August 2016 financing		53,506		53,506	$	30.00		February 2, 2022
Warrants related to August 2016 financing		4,994		4,994	$	38.55		August 2, 2021
Warrants related to December 2016 financing		685,667		685,667	$	20.00		December 14, 2021
Warrants related to March 2018 financing		158,100		158,100	$	11.40		September 9, 2023
Warrants related to March 2018 financing		11,067		11,067	$	15.80		March 6, 2023
Warrants related to July 2018 financing		2,571,429		2,571,429	$	3.50		July 25, 2023
Warrants related to July 2018 financing		154,286		154,286	$	4.38		July 25, 2023
Warrants related to May 2019 financing		119,000		119,000	$	1.25		May 23, 2024
Warrants related to October 2019 financing		11,438,716		11,438,716	$	0.25		October 10, 2024
Warrants related to October 2019 financing		828,380		—	$	0.31		October 8, 2024