Consolidated Statements of Changes in 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 (loss)/income	(43,796,685)			(43,796,685)
Issuance of shares for private placement, net of issuance costs (in shares)		22,222,223
Issuance of shares for private placement, net of issuance costs	96,030,003	$ 222,222	95,807,781
Issuance of shares due to vesting restricted shares (in shares)		65,257
Issuance of shares due to vesting of restricted shares		$ 653	(653)
Cash used to settle net share equity awards	(289,539)		(289,539)
Stock-based compensation	8,738,615		8,738,615
Ending balance (in shares) at Dec. 31, 2017		70,394,307
Ending balance at Dec. 31, 2017	461,165,033	$ 703,944	887,625,902	(427,164,813)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss)/income	12,574,684			12,574,684
Issuance of shares due to vesting restricted shares (in shares)		661,093
Issuance of shares due to vesting of restricted shares	4,866	$ 6,611	(1,745)
Cash used to settle net share equity awards	(2,559,104)		(2,559,104)
Stock-based compensation	9,207,480		9,207,480
Ending balance (in shares) at Dec. 31, 2018		71,055,400
Ending balance at Dec. 31, 2018	479,605,849	$ 710,555	894,272,533	(415,377,239)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss)/income	(21,697,115)			(21,697,115)
Proceeds received from the Share Lending Agreement	35,829		35,829
Issuance of shares due to vesting restricted shares (in shares)		446,806
Issuance of shares due to vesting of restricted shares		$ 4,467	(4,467)
Equity component of Convertible Bond Debt, net of equity issuance costs	20,175,803		20,175,803
Cash used to settle net share equity awards	(1,443,753)		(1,443,753)
Stock-based compensation	4,826,324		4,826,324
Ending balance (in shares) at Dec. 31, 2019		71,502,206
Ending balance at Dec. 31, 2019	$ 481,502,937	$ 715,022	$ 917,862,269	$ (437,074,354)