Fair Value of Financial Assets and Liabilities - Derivative Instruments (Fair Value of Financial Liabilities Measured on Recurring Basis) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Derivative liability	$ 292,000	$ 2,443,000
Total liabilities	292,000	2,443,000
Dilutive Financing Derivative Liability [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Derivative liability		126,000
November 2016 Warrant Derivative Liability [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Warrant liability	260,000
Derivative liability	260,000	2,043,000
June 2016 Offering Warrants [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Warrant liability	32,000	274,000
Derivative liability	32,000	274,000
2011 Warrants [Member] | November 2016 Warrant Derivative Liability [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Warrant liability		2,043,000
Fair Value, Inputs, Level 3 [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Total liabilities	292,000	2,443,000
Fair Value, Inputs, Level 3 [Member] | Dilutive Financing Derivative Liability [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Derivative liability		126,000
Fair Value, Inputs, Level 3 [Member] | November 2016 Warrant Derivative Liability [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Warrant liability	260,000	2,043,000
Fair Value, Inputs, Level 3 [Member] | June 2016 Offering Warrants [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Warrant liability	$ 32,000	$ 274,000