Significant Accounting Policies (Narrative) (Details)				3 Months Ended		6 Months Ended	12 Months Ended		24 Months Ended
	Mar. 22, 2018 USD ($)	Jan. 12, 2018 USD ($)	Apr. 24, 2017 $ / shares shares	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Apr. 23, 2017 shares
Impairment of long-lived assets									$ 0
Proceeds from equity offerings, gross	$ 3,000,000	$ 4,000,000
Reverse stock split, description							1-for-10 (1:10) reverse stock split of its common stock, par value $0.01 per share
Conversion ratio of reverse stock split			10
Common stock, par value (in dollars per share) | $ / shares			$ 0.01				$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized | shares			67,000,000				217,000,000	67,000,000	67,000,000	670,000,000
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Unrecognized tax benefits							$ 1,700,000	$ 2,100,000	$ 2,100,000
Australian Taxation Office [Member]
Tax rebates received				$ 1,200,000	$ 2,000,000
Staph Program [Member]
Impairment of long-lived assets							$ 0
Discount rate							19.40%
In-process resesarch and development						$ 2,800,000
Pseudomonas Program [Member]
In-process resesarch and development						1,900,000
In Process Research and Development [Member]
Impairment of in-process research and development						5,800,000	$ 1,900,000	5,800,000
Income tax expense (benefit) relating to impairment charge						$ (1,300,000)	(328,000)	$ 1,300,000
Patents [Member]
Finite-lived intangible assets, gross							493,000
Accumulated amortization							$ 248,000