Stock Purchase Warrants (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Beginning Balance			$ 10,567
Change in fair value of warrant liability	$ (3,513)	$ 3,895	(3,015)	$ 8,047
Ending Balance	$ 7,552	$ 14,800	$ 7,552	$ 14,800