Income Tax (Schedule of Income Tax Rate Differences) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal income tax expense at statutory rate	$ (4,495,000)	$ (4,411,000)
Increase (reduction) in income tax resulting from:
State and local income taxes, net of federal benefit	(194,000)	69,000
Foreign rate differential	16,000	(18,000)
Non-deductible expenses	9,000	8,000
Prior-period true-up		547,000
Research & development credit	(409,000)	(575,000)
Stock-based compensation	84,000	113,000
Acquisition costs	96,000
Reserve for loss carryforwards limited by Sec. 382	(541,000)
Tax reform impact	8,024,000
Other	45,460	(1,000)
Increase in valuation allowance	(3,445,000)	4,268,000
Total	$ (809,540)