CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($)	Common Stock [Member]	Additional Paid in Capital [Member]	Accumulated Deficit [Member]	Total
Beginning balance at Dec. 31, 2013	$ 144,977	$ 135,086,056	$ (80,532,626)	$ 54,698,407
Beginning balance (in shares) at Dec. 31, 2013	144,976,757
Increase (Decrease) in Stockholders' Deficiency [Roll Forward]
Shares issued in offerings, net of cost	$ 9,850	42,761,503		42,771,353
Shares issued in offerings, net of cost (in shares)	9,850,106
Shares issued for exercise of options, net	$ 855	344,891		345,746
Shares issued for exercise of options, net (in shares)	854,573
Shares issued for exercise of warrants, net	$ 365	180,635		181,000
Shares issued for exercise of warrants, net (in shares)	365,583
Shares issued for exercise of restricted stock units	$ 50	(50)
Shares issued for exercise of restricted stock units (in shares)	50,000
Share-based compensation		4,609,811		4,609,811
Net loss			(54,217,210)	(54,217,210)
Ending balance at Dec. 31, 2014	$ 156,097	182,982,846	(134,749,836)	48,389,107
Ending balance (in shares) at Dec. 31, 2014	156,097,019
Increase (Decrease) in Stockholders' Deficiency [Roll Forward]
Shares issued in offerings, net of cost	$ 20,040	91,354,609		91,374,649
Shares issued in offerings, net of cost (in shares)	20,040,359
Shares issued for exercise of options, net	$ 613	1,231,966		1,232,579
Shares issued for exercise of options, net (in shares)	612,981
Shares issued for exercise of warrants, net	$ 1,178	364,822		366,000
Shares issued for exercise of warrants, net (in shares)	1,177,682
Share-based compensation		6,777,835		6,777,835
Net loss			(85,077,024)	(85,077,024)
Ending balance at Dec. 31, 2015	$ 177,928	282,712,078	(219,826,860)	$ 63,063,146
Ending balance (in shares) at Dec. 31, 2015	177,928,041			177,928,041
Increase (Decrease) in Stockholders' Deficiency [Roll Forward]
Shares issued in offerings, net of cost	$ 17,424	134,846,051		$ 134,863,475
Shares issued in offerings, net of cost (in shares)	17,424,242
Shares issued for exercise of options, net	$ 613	988,447		989,060
Shares issued for exercise of options, net (in shares)	613,195
Shares issued for exercise of warrants, net	$ 723	1,372,277		1,373,000
Shares issued for exercise of warrants, net (in shares)	722,744
Share-based compensation		17,076,199		17,076,199
Net loss			(89,875,459)	(89,875,459)
Ending balance at Dec. 31, 2016	$ 196,688	$ 436,995,052	$ (309,702,319)	$ 127,489,421
Ending balance (in shares) at Dec. 31, 2016	196,688,222			196,688,222