Income Taxes (Components of Deferred Tax Assets) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets, Net [Abstract]
Net operating loss carry-forwards	$ 44,049,000	$ 67,479,000
Research and development and other tax credits, net	3,109,000	3,109,000
Stock-based compensation	188,000	795,000
Other	165,000	301,000
Deferred tax assets, gross	47,511,000	71,684,000
Valuation allowance for deferred tax assets	(47,511,000)	(71,684,000)
Deferred Tax Liabilities, Net [Abstract]
In-process research and development	(1,147,000)	(2,449,000)
Total deferred tax liabilities	$ (1,147,000)	$ (2,449,000)