Condensed Consolidated Statements of Comprehensive Loss - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (4,797,270)	$ (4,102,729)	$ (10,168,116)	$ (9,482,676)
Other comprehensive income (loss), net of tax effect:
Unrealized gain (loss) on short-term investments	819	(188)	4,172	(11,339)
Foreign currency translation adjustment	(9,194)		(2,755)
Total other comprehensive income (loss)	(8,375)	(188)	1,417	(11,339)
Comprehensive loss	$ (4,805,645)	$ (4,102,917)	$ (10,166,699)	$ (9,494,015)