Statements of Stockholders' Equity - USD ($)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Balance at Dec. 31, 2015	$ 8,724,998	$ 97	$ 54,277,716	$ (45,545,445)	$ (7,370)
Balance (in shares) at Dec. 31, 2015		9,683,741
Employee stock-based compensation, net	1,785,326		1,785,326
Employee stock-based compensation, net (in shares)		(43,166)
Convertible loan payment issued in equity to related party	$ 1,200,000	$ 9	1,199,991
Convertible loan payment issued in equity to related party (in shares)		960,000
Issuance of common stock under employee stock plans (in shares)	21,616
Sale of common stock, net of issuance costs	$ 11,063,887	$ 102	11,063,785
Sale of common stock, net of issuance costs (in shares)		10,223,298
Unrealized gain (loss) on investments	478				478
Net loss	(14,731,822)			(14,731,822)
Balance at Dec. 31, 2016	8,042,867	$ 208	68,326,818	(60,277,267)	(6,892)
Balance (in shares) at Dec. 31, 2016		20,823,873
Employee stock-based compensation, net	1,429,753		1,429,753
Employee stock-based compensation, net (in shares)		(12,534)
Issuance of common stock under employee stock plans	$ 73,141	$ 1	73,140
Issuance of common stock under employee stock plans (in shares)	42,823	87,978
Issuance of common stock from warrant exercises	$ 678,451	$ 10	678,441
Issuance of common stock from warrant exercises (in shares)		1,022,119
Sale of common stock, net of issuance costs	23,831,166	$ 139	23,831,027
Sale of common stock, net of issuance costs (in shares)		13,895,668
Unrealized gain (loss) on investments	(12,877)				(12,877)
Net loss	(20,577,665)			(20,577,665)
Balance at Dec. 31, 2017	$ 13,464,836	$ 358	$ 94,339,179	$ (80,854,932)	$ (19,769)
Balance (in shares) at Dec. 31, 2017		35,817,104