Stockholders' Equity (Schedule of Warrants By Exercise Price) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares		266,810	113,672
Exercise Price		$ 19.57	$ 39.32
3/10/2011 [Member]
Issuance Date	Mar. 10, 2011
Number of Shares	1,738
Exercise Price	$ 4.80
Expiration Date	Mar. 10, 2021
7/23/2013 [Member]
Issuance Date	Jul. 23, 2013
Number of Shares	12,500
Exercise Price	$ 125.00
Expiration Date	Jul. 23, 2018
3/23/2016 [Member]
Issuance Date	Mar. 23, 2016
Number of Shares	296,159
Exercise Price	$ 10.00
Expiration Date	Mar. 23, 2021