Fair Value Measurements (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2015
Reconciliations of the beginning and ending balances for liabilities measured at fair value on a recurring basis using significant unobservable inputs (i.e. Level 3)
Balance at the beginning of the period	$ 28,829,849
Change in fair value of common stock warrants	68,433,468
Issuance of common stock warrants	11,773,240
Exercise of common stock warrants	(83,294,149)
Balance at the end of the period	25,742,408
Warrants
Reconciliations of the beginning and ending balances for liabilities measured at fair value on a recurring basis using significant unobservable inputs (i.e. Level 3)
Balance at the beginning of the period		9,418,413
Change in fair value of common stock warrants		(1,768,795)
Balance at the end of the period		$ 7,649,618