Fair Value Measurements (Change in Fair Value of Derivative Liabilities) (Details)	6 Months Ended
	Jun. 30, 2017 USD ($)
Derivatives And Fair Value [Line Items]
Balance, derivative liability	$ 2,443,000
Changes in estimated fair value	(2,034,000)
Settlement of liability	(22,000)
Balance, derivative liability	387,000
Dilutive Financing Derivative Liability [Member]
Derivatives And Fair Value [Line Items]
Balance, derivative liability	126,000
Changes in estimated fair value	(104,000)
Settlement of liability	(22,000)
Balance, derivative liability	358,000
November 2016 Warrant Derivative Liability [Member]
Derivatives And Fair Value [Line Items]
Balance, derivative liability	2,043,000
Changes in estimated fair value	(1,685,000)
Balance, derivative liability	358,000
June 2016 Offering Liability [Member]
Derivatives And Fair Value [Line Items]
Balance, derivative liability	274,000
Changes in estimated fair value	(245,000)
Balance, derivative liability	$ 29,000