Stockholders' Equity (Details)		1 Months Ended		12 Months Ended
	Nov. 10, 2010 item $ / shares shares	Jul. 31, 2017 USD ($) $ / shares shares	Mar. 31, 2015 USD ($) item shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Stockholders' Equity
Shares of common stock issued		1,325,000	1,437,000
Net proceeds from issuance of common stock | $		$ 1,987,000	$ 21,400,000	$ 1,967,000	$ 364,000	$ 23,140,000
Number of executive officers | item			2
Shares purchased by executive officers			40,625
Sale of Stock, Price Per Share | $ / shares		$ 1.70
Shares of common stock available by warrant		0.5
Warrants available to purchase		662,500
Exercise price of warrants | $ / shares	$ 4.80	$ 2.35
Number of preferred share purchase rights declared as dividend for each outstanding share of common stock | item	1
Number of shares of Series AA Preferred Stock that a registered holder of right is entitled to purchase	0.001
Percentage of the company's common stock acquired by a third party upon which the rights become exercisable	15.00%
Minimum percentage of the company's common stock that must receive a tender offer from a third party upon which the rights become exercisable	15.00%