Income Taxes (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Change in the valuation allowance
Valuation allowance, at beginning of year	$ 47,858,000	$ 41,412,000	$ 11,348,000
Increase in valuation allowance	16,591,000	6,446,000	30,064,000
Valuation Allowances, at end of year	64,449,000	47,858,000	41,412,000
Gross amount of unrealized net operating loss carryforwards resulting from stock-based compensation	30,100,000
Tax-effected amount of unrealized net operating loss carryforwards resulting from stock-based compensation	11,100,000
Increase in additional paid in capital if and when deferred tax assets are ultimately realized	11,100,000
Reconciliation of the total amounts of unrecognized tax benefits
Unrecognized tax benefit beginning of year	(4,000)	(4,000)
Additions based on current year tax positions	21,000		610,000
Additions for prior years' tax positions	29,000
Reductions for prior years' tax positions			(614,000)
Unrecognized tax benefit end of year	46,000	(4,000)	(4,000)
Maximum
Accrued interest and penalties
Accrued interest and penalties	$ 100,000