Condensed Consolidated Statements of Stockholders' Equity - USD ($)		Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning Balance (in shares) at Dec. 31, 2016			48,106,827
Beginning Balance at Dec. 31, 2016		$ 400,482,639	$ 481,069	$ 783,369,698	$ (383,368,128)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income/(loss)		(16,956,914)			(16,956,914)
Issuance of shares (in shares)			22,222,223
Issuance of shares for private placement, net of issuance costs		96,030,003	$ 222,222	95,807,781
Stock-based compensation		4,648,751		4,648,751
Ending Balance (in shares) at Jun. 30, 2017			70,329,050
Ending Balance at Jun. 30, 2017		484,204,479	$ 703,291	883,826,230	(400,325,042)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	[1]	(787,110)			(787,110)
Beginning Balance (in shares) at Dec. 31, 2017			70,394,307
Beginning Balance at Dec. 31, 2017		461,165,033	$ 703,944	887,625,902	(427,164,813)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income/(loss)		3,503,512			3,503,512
Issuance of shares (in shares)			122,159
Issuance of shares for private placement, net of issuance costs		0	$ 1,212	(1,212)
Cash received due to exercise of stock options		4,865	$ 9	4,856
Cash used to settle net share equity awards		(255,114)		(255,114)
Stock-based compensation		5,920,510		5,920,510
Ending Balance (in shares) at Jun. 30, 2018			70,516,466
Ending Balance at Jun. 30, 2018		$ 469,551,696	$ 705,165	$ 893,294,942	$ (424,448,411)

[1] The opening accumulated deficit has been adjusted on January 1, 2018 in connection with adoption of Accounting Standards Update 2014-09 ("ASC 606"). Please refer to Note 2 "Recently Adopted Accounting Pronouncements" to the condensed consolidated financial statements.