Income Taxes (Schedule of Deferred Tax Assets) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
Net operating loss carryforwards	$ 37,191,826	$ 24,767,569
R&D credit carryforwards	7,388,463	6,546,049
Temporary differences	4,624,832	2,408,108
Deferred tax assets before valuation allowance	49,205,121	33,721,726
Valuation allowance	(49,205,121)	(33,721,726)
Net deferred tax assets	$ 0	$ 0

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

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

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