Condensed Consolidated Statements of Comprehensive Loss - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (5,370,846)	$ (5,379,947)
Other comprehensive income (loss), net of tax effect:
Unrealized gain (loss) on short-term investments	3,353	(11,151)
Foreign currency translation adjustment	6,439
Total other comprehensive income (loss)	9,792	(11,151)
Comprehensive loss	$ (5,361,054)	$ (5,391,098)