Stockholders' Equity (Schedule of Warrants By Exercise Price) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Shares	3,063,636	465,303	266,810
Exercise Price	$ 2.56	$ 11.60	$ 19.57
3/10/2011
Issuance Date	Mar. 10, 2011
Number of Shares	1,738
Exercise Price	$ 4.80
Expiration Date	Mar. 10, 2021
3/23/2016
Issuance Date	Mar. 23, 2016
Number of Shares	296,159
Exercise Price	$ 10.00
Expiration Date	Mar. 23, 2021
5/7/2018
Issuance Date	May 07, 2018
Number of Shares	4,132,833
Exercise Price	$ 1.58
Expiration Date	May 08, 2023
11/26/2018
Issuance Date	Nov. 26, 2018
Number of Shares	4,600,000
Exercise Price	$ 1.65
Expiration Date	Nov. 26, 2023