Stockholders' Equity (Details) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Warrant [Member]
Shares
Outstanding, beginning balance	39,818,347	26,397,410
Expired or cancelled during the period	(726,416)	(546,667)
Exercised during the period	0	(12,270,853)
Issued in connection with tender offer exercise	0	26,479,217
Outstanding, ending balance	39,091,931	40,059,107
Stock options [Member]
Shares
Outstanding, beginning balance	26,865,017	10,337,113
Issued during period	4,698,759	6,836,016
Expired or cancelled during the period	(716,830)	(85,000)
Outstanding, ending balance	30,846,946	17,088,129