Condensed Consolidated Statements of Comprehensive Loss - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (4,740,232)	$ (4,843,408)	$ (14,908,348)	$ (14,326,084)
Other comprehensive income (loss), net of tax effect:
Unrealized gain (loss) on short-term investments	(1,864)	2,457	2,308	(8,882)
Foreign currency translation adjustment	37,575		34,820
Total other comprehensive income (loss)	35,711	2,457	37,128	(8,882)
Comprehensive loss	$ (4,704,521)	$ (4,840,951)	$ (14,871,220)	$ (14,334,966)