Fair Value of Financial Assets and Liabilities - Derivative Instruments (Narrative) (Details) - USD ($)			1 Months Ended	6 Months Ended	12 Months Ended
	Jun. 27, 2017	Apr. 08, 2016	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Sep. 19, 2017	Jun. 29, 2017	Apr. 24, 2017	Apr. 23, 2017	Nov. 30, 2016	Jun. 30, 2016
Derivatives And Fair Value [Line Items]
Remaining shares authorized for issuance					67,000,000	67,000,000			67,000,000	670,000,000
Derivative liability					$ 292,000	$ 2,443,000
Common stock closing price					$ 1.01	$ 4.40	$ 0.99
Fair value of shares issued					$ 22,000
Dilutive Financing Derivative Liability [Member]
Derivatives And Fair Value [Line Items]
Derivative liability						$ 126,000
Fair value of shares issued					22,000
November 2016 Warrant Derivative Liability [Member]
Derivatives And Fair Value [Line Items]
Number of securities called by warrants											533,500
Derivative liability					$ 260,000	$ 2,043,000
Common stock closing price					$ 1.01	$ 4.40
Common Stock Issuance Agreement [Member]
Derivatives And Fair Value [Line Items]
Number of securities called by warrants		31,519
Shares issued per agreement		85,346	523,210
Remaining shares authorized for issuance						28,684
Future shares of common stock approved to be issued per agreement						28,684
Common Stock Issuance Agreement Amendment [Member]
Derivatives And Fair Value [Line Items]
Shares issued per agreement				28,684
Derivative liability								$ 22,000
Future shares of common stock approved to be issued per agreement	28,684
Fair value of shares issued				$ 22,000
June 2016 Offering Warrants [Member]
Derivatives And Fair Value [Line Items]
Number of securities called by warrants												106,383