Common Stock (Narrative) (Details)					12 Months Ended
	Mar. 29, 2017 USD ($) $ / shares shares	Mar. 15, 2017 USD ($) shares	Feb. 28, 2017 $ / shares shares	Jan. 24, 2017 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($)	Sep. 20, 2017 USD ($)
Class of Stock [Line Items]
Warrant fair value adjustment | $						$ 289,000	$ 12,000
Reverse stock split, conversion ratio		0.1538
Reverse stock split, fractional shares issued | shares		0
Reverse stock split, shares settled in cash | shares		73
Reverse stock split, shares settled in cash, amount | $		$ 1,000				1,000
Proceeds from common stock issued | $					$ 260,000	$ 47,468,000
Underwritten Public Offering [Member]
Class of Stock [Line Items]
Shares issued, price per share | $ / shares	$ 10.50
Issuance of common stock, shares | shares	4,772,500
Proceeds from common stock issued | $	$ 45,850,000
ATM Program [Member]
Class of Stock [Line Items]
Shares issued, price per share | $ / shares					$ 10.40	$ 10.15
Issuance of common stock, shares | shares					28,474	169,004
Proceeds from common stock issued | $					$ 296,000	$ 1,715,000
Net proceeds from common stock issue | $					$ 260,000	$ 1,619,000
ATM Program, Since Inception [Member]
Class of Stock [Line Items]
Shares issued, price per share | $ / shares					$ 10.18
Issuance of common stock, shares | shares					197,478
Proceeds from common stock issued | $					$ 2,011,000
Net proceeds from common stock issue | $					$ 1,879,000
Maximum [Member] | ATM Program [Member]
Class of Stock [Line Items]
Equity distribution agreement, aggregate price of shares available for sale | $								$ 50,000,000
Minimum [Member] | ATM Program [Member]
Class of Stock [Line Items]
Public float required to sell shares of common stock | $								$ 75,000,000
Pursuant To Full Exercise Of An Option To Purchase Additional Shares Of Common Stock Granted To Underwriters [Member] | Underwritten Public Offering [Member]
Class of Stock [Line Items]
Issuance of common stock, shares | shares	622,500
New Warrants [Member]
Class of Stock [Line Items]
Shares issued upon conversion | shares				23,160
Common stock warrants, exercise price | $ / shares				$ 0.0065
Warrant expiration				Jan. 24, 2019
Warrant fair value adjustment | $				$ 289,000
Real Estate Strategies, L.P. [Member] | Warrants [Member]
Class of Stock [Line Items]
Shares converted | shares				576,923
Common Stock [Member]
Class of Stock [Line Items]
Shares issued upon conversion | shares			6,004,957
Number of shares called by warrant | shares				23,160
Shares issued, price per share | $ / shares			$ 10.40
Issuance of common stock, shares | shares					28,000	4,972,000