Income Tax (Schedule of Income Tax Rate Differences) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal income tax expense at statutory rate	$ (4,411,000)	$ (7,182,000)
Increase (reduction) in income tax resulting from:
State and local income taxes, net of federal benefit	69,000	(420,000)
Foreign rate differential	(18,000)	64,000
Non-deductible expenses	8,000
Prior-period true-up	547,000	(489,000)
Research & development credit	(575,000)	(171,000)
Stock-based compensation	113,000	194,000
Other	(1,000)
Increase in valuation allowance	4,268,000	8,004,000
Total