Income Taxes (Deferred tax assets (liabilities) (Detail) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Deferred tax asset:
Net operating loss carryforwards	$ 29,122,000	$ 26,754,000
Accrued expenses	87,000	105,000
Amortization of definite lived intangible assets	10,000	12,000
Non-qualified stock option compensation	315,000	113,000
Depreciation	72,000	97,000
Deferred revenue	880,000	930,000
Other	139,000	146,000
Patents	(23,000)	(77,000)
State net operating loss carryforwards, net of federal tax benefit	579,000	214,000
Research tax credit carryforwards	2,274,000	2,169,000
Total deferred tax assets	33,455,000	30,463,000
Valuation allowance	(33,455,000)	(30,463,000)
Net deferred tax assets	$ 0	$ 0