Income Taxes (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Summary of deferred tax assets
Net operating loss carryforward	$ 27,181,000	$ 31,338,000
Capitalized research and development expenses	8,115,000	10,402,000
License fees	349,000	325,000
Stock-based compensation expense	2,264,000	2,264,000
Other	917,000	737,000
Gross deferred tax assets	38,826,000	45,066,000
Valuation allowance	(38,826,000)	(45,066,000)
Net deferred tax assets

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from in-process research and development costs expensed in connection with a business combination.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from compensation and benefits costs.

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- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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