Statements of Redeemable Convertible Preferred Stock and Stockholders Equity (Deficit) - USD ($)	Total	Common Stock	Additional Paid-In-Capital	Treasury Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock	Series C-1 Redeemable Convertible Preferred Stock	Series C-2 Redeemable Convertible Preferred Stock	Series D Redeemable Convertible Preferred Stock	Series E Redeemable Convertible Preferred Stock
Balance at Dec. 31, 2014	$ (69,669,926)	$ 333	$ (1,426,556)	$ (75,000)		$ (68,168,703)	$ 1,402,687	$ 2,099,310	$ 4,567,525	$ 2,223,506	$ 37,174,666	$ 8,454,899
Balance, shares at Dec. 31, 2014		332,607					1,292,084	6,789,712	13,242,612	9,948,331	139,529,173	45,938,041
Exercise of Series D and Series E warrants											$ 93,550	$ 11,312
Exercise of Series D and Series E warrants, shares											723,505	51,681
Exercise of stock options	34,881	$ 14	34,867
Exercise of stock options, shares		13,960
Stock issued under stock purchase plan	$ 20,000	$ 4	19,996
Stock issued under stock purchase plan, shares	4,184	4,184
Stock-based compensation expense	$ 405,426		405,426
Accretion of redeemable convertible preferred stock issuance costs	(35,046)		(35,046)				$ 320	$ 839	$ 1,538	$ 2,113	$ 18,109	$ 12,127
Accretion of Series E warrant discount	(127,616)		(127,616)									127,616
Accretion of Series D and E redeemable convertible preferred stock dividends	(1,165,932)		(1,165,932)								876,955	288,977
Conversion of outstanding principal and accrued interest on convertible notes by issuance of common stock	4,544,384	$ 324	4,544,060
Conversion of outstanding principal and accrued interest on convertible notes by issuance of common stock, shares		324,591
Conversion of warrants from warrants for preferred stock to warrants for common stock	1,616,140		1,616,140
Optional conversion of preferred stock to common	57,356,049	$ 2,509	57,353,540				$ (1,403,007)	$ (2,100,149)	$ (4,569,063)	$ (2,225,619)	$ (38,163,280)	$ (8,894,931)
Optional conversion of preferred stock to common, shares		2,508,824					(1,292,084)	(6,789,712)	(13,242,612)	(9,948,331)	(140,252,678)	(45,989,722)
Issuance of common stock from initial public offering	45,354,186	$ 3,660	45,350,526
Issuance of common stock from initial public offering, shares		3,660,076
Net loss	(21,397,791)					(21,397,791)
Other comprehensive income (loss)	(41,357)				$ (41,357)
Balance at Dec. 31, 2015	16,893,398	$ 6,844	106,569,405	(75,000)	(41,357)	(89,566,494)
Balance, shares at Dec. 31, 2015		6,844,242
Stock issued for payment of 2015 annual bonus	364,910	$ 133	364,777
Stock issued for payment of 2015 annual bonus, shares		133,179
Exercise of stock options	23,851	$ 11	23,840
Exercise of stock options, shares		11,093
Stock issued under stock purchase plan	273,218	$ 80	273,138
Stock issued under stock purchase plan, shares		79,962
Stock-based compensation expense	903,547		903,547
Vesting of restricted stock units	37	$ 37
Vesting of restricted stock units, shares		36,762
Stock issued for private investment	1,825,000	$ 833	1,824,167
Stock issued for private investment, shares		833,333
Growth Term Loan B warrant discount	122,460		122,460
Net loss	(26,039,550)					(26,039,550)
Other comprehensive income (loss)	40,267				40,267
Balance at Dec. 31, 2016	$ (5,592,862)	$ 7,938	$ 110,081,334	$ (75,000)	$ (1,090)	$ (115,606,044)
Balance, shares at Dec. 31, 2016		7,938,571