CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($)	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Preferred stock, beginning balance (shares) at Dec. 31, 2017		0
Equity, beginning balance at Dec. 31, 2017	$ 29,105,888	$ 0	$ 1,780	$ 140,184,630	$ (1,247)	$ (111,079,275)
Common stock, beginning balance (shares) at Dec. 31, 2017			17,797,178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (shares)			171,029
Vesting of restricted common stock	0		$ 17	(17)
Issuance of common stock from option exercises (shares)			12,645
Issuance of common stock from option exercises	54,913		$ 1	54,912
Stock-based compensation expense	908,940			908,940
Unrealized gain (loss) on available-for-sale securities	1,340				1,340
Net loss	(8,223,227)					(8,223,227)
Preferred stock, ending balance (shares) at Mar. 31, 2018		0
Equity, ending balance at Mar. 31, 2018	21,888,071	$ 0	$ 1,798	141,148,465	93	(119,262,285)
Common stock, ending balance (shares) at Mar. 31, 2018			17,980,852
Preferred stock, beginning balance (shares) at Dec. 31, 2017		0
Equity, beginning balance at Dec. 31, 2017	29,105,888	$ 0	$ 1,780	140,184,630	(1,247)	(111,079,275)
Common stock, beginning balance (shares) at Dec. 31, 2017			17,797,178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain (loss) on available-for-sale securities	1,247
Net loss	(17,275,099)
Preferred stock, ending balance (shares) at Jun. 30, 2018		0
Equity, ending balance at Jun. 30, 2018	13,410,196	$ 0	$ 1,807	141,722,546	0	(128,314,157)
Common stock, ending balance (shares) at Jun. 30, 2018			18,066,142
Preferred stock, beginning balance (shares) at Mar. 31, 2018		0
Equity, beginning balance at Mar. 31, 2018	21,888,071	$ 0	$ 1,798	141,148,465	93	(119,262,285)
Common stock, beginning balance (shares) at Mar. 31, 2018			17,980,852
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (shares)			625
Vesting of restricted common stock	0
Issuance of common stock from option exercises (shares)			84,665
Issuance of common stock from option exercises	63,097		$ 9	63,088
Stock-based compensation expense	510,993			510,993
Unrealized gain (loss) on available-for-sale securities	(93)				(93)
Net loss	(9,051,872)					(9,051,872)
Preferred stock, ending balance (shares) at Jun. 30, 2018		0
Equity, ending balance at Jun. 30, 2018	$ 13,410,196	$ 0	$ 1,807	141,722,546	0	(128,314,157)
Common stock, ending balance (shares) at Jun. 30, 2018			18,066,142
Preferred stock, beginning balance (shares) at Dec. 31, 2018	0	0
Equity, beginning balance at Dec. 31, 2018	$ 9,282,756	$ 0	$ 1,807	142,242,224	0	(132,961,275)
Common stock, beginning balance (shares) at Dec. 31, 2018	18,067,392		18,067,392
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (shares)			625
Vesting of restricted common stock	$ 0
Stock-based compensation expense	220,975			220,975
Net loss	(2,230,430)					(2,230,430)
Preferred stock, ending balance (shares) at Mar. 31, 2019		0
Equity, ending balance at Mar. 31, 2019	$ 7,273,301	$ 0	$ 1,807	142,463,199	0	(135,191,705)
Common stock, ending balance (shares) at Mar. 31, 2019			18,068,017
Preferred stock, beginning balance (shares) at Dec. 31, 2018	0	0
Equity, beginning balance at Dec. 31, 2018	$ 9,282,756	$ 0	$ 1,807	142,242,224	0	(132,961,275)
Common stock, beginning balance (shares) at Dec. 31, 2018	18,067,392		18,067,392
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from option exercises (shares)	0
Unrealized gain (loss) on available-for-sale securities	$ 0
Net loss	$ (3,615,207)
Preferred stock, ending balance (shares) at Jun. 30, 2019	0	0
Equity, ending balance at Jun. 30, 2019	$ 6,101,071	$ 0	$ 1,807	142,675,746	0	(136,576,482)
Common stock, ending balance (shares) at Jun. 30, 2019	18,068,642		18,068,642
Preferred stock, beginning balance (shares) at Mar. 31, 2019		0
Equity, beginning balance at Mar. 31, 2019	$ 7,273,301	$ 0	$ 1,807	142,463,199	0	(135,191,705)
Common stock, beginning balance (shares) at Mar. 31, 2019			18,068,017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (shares)			625
Vesting of restricted common stock	0
Stock-based compensation expense	212,547			212,547
Unrealized gain (loss) on available-for-sale securities	0
Net loss	$ (1,384,777)					(1,384,777)
Preferred stock, ending balance (shares) at Jun. 30, 2019	0	0
Equity, ending balance at Jun. 30, 2019	$ 6,101,071	$ 0	$ 1,807	$ 142,675,746	$ 0	$ (136,576,482)
Common stock, ending balance (shares) at Jun. 30, 2019	18,068,642		18,068,642