Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($)	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 31, 2018	$ 90,264,769	$ 3,894	$ 304,813,603	$ (214,552,728)
Balance (in shares) at Dec. 31, 2018		38,937,971
Exercise of stock options	525,000	$ 9	524,991
Exercise of stock options (in shares)		87,500
Stock-based compensation	2,461,699		2,461,699
Net income (loss)	(15,827,200)			(15,827,200)
Balance at Mar. 31, 2019	77,424,268	$ 3,903	307,800,293	(230,379,928)
Balance (in shares) at Mar. 31, 2019		39,025,471
Balance at Dec. 31, 2018	90,264,769	$ 3,894	304,813,603	(214,552,728)
Balance (in shares) at Dec. 31, 2018		38,937,971
Net income (loss)	(42,265,674)
Balance at Sep. 30, 2019	55,527,375	$ 3,903	312,341,874	(256,818,402)
Balance (in shares) at Sep. 30, 2019		39,025,471
Balance at Mar. 31, 2019	77,424,268	$ 3,903	307,800,293	(230,379,928)
Balance (in shares) at Mar. 31, 2019		39,025,471
Stock-based compensation	2,320,392		2,320,392
Net income (loss)	(12,476,471)			(12,476,471)
Balance at Jun. 30, 2019	67,268,189	$ 3,903	310,120,685	(242,856,399)
Balance (in shares) at Jun. 30, 2019		39,025,471
Stock-based compensation	2,221,189		2,221,189
Net income (loss)	(13,962,003)			(13,962,003)
Balance at Sep. 30, 2019	55,527,375	$ 3,903	312,341,874	(256,818,402)
Balance (in shares) at Sep. 30, 2019		39,025,471
Balance at Dec. 31, 2019	$ 27,779,543	$ 3,908	314,511,853	(286,736,218)
Balance (in shares) at Dec. 31, 2019	39,084,121	39,084,121
Exercise of stock options	$ 797,629	$ 14	797,615
Exercise of stock options (in shares)		135,013
Stock-based compensation	2,198,187		2,198,187
Net income (loss)	(12,151,165)			(12,151,165)
Balance at Mar. 31, 2020	18,624,194	$ 3,922	317,507,655	(298,887,383)
Balance (in shares) at Mar. 31, 2020		39,219,134
Balance at Dec. 31, 2019	$ 27,779,543	$ 3,908	314,511,853	(286,736,218)
Balance (in shares) at Dec. 31, 2019	39,084,121	39,084,121
Net income (loss)	$ 9,265,598
Balance at Sep. 30, 2020	$ 58,022,903	$ 4,267	335,489,256	(277,470,620)
Balance (in shares) at Sep. 30, 2020	42,674,491	42,674,491
Balance at Mar. 31, 2020	$ 18,624,194	$ 3,922	317,507,655	(298,887,383)
Balance (in shares) at Mar. 31, 2020		39,219,134
Issuance of common stock in public offering	5,178,460	$ 136	5,178,324
Issuance of common stock in public offering		1,361,956
Costs related to issuance of common stock	(219,517)		(219,517)
Exercise of stock options	346,026	$ 7	346,019
Exercise of stock options (in shares)		63,749
Stock-based compensation	3,485,482		3,485,482
Net income (loss)	29,529,376			29,529,376
Balance at Jun. 30, 2020	56,944,021	$ 4,065	326,297,963	(269,358,007)
Balance (in shares) at Jun. 30, 2020		40,644,839
Issuance of common stock in public offering	7,371,609	$ 201	7,371,408
Issuance of common stock in public offering		2,019,652
Costs related to issuance of common stock	(236,149)		(236,149)
Vesting of restricted stock units		$ 1	(1)
Vesting of restricted stock units (in shares)		10,000
Stock-based compensation	2,056,035		2,056,035
Net income (loss)	(8,112,613)			(8,112,613)
Balance at Sep. 30, 2020	$ 58,022,903	$ 4,267	$ 335,489,256	$ (277,470,620)
Balance (in shares) at Sep. 30, 2020	42,674,491	42,674,491