Warrants - Schedule of Key Terms of Placement Warrants (Detail) - $ / shares	1 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2019	Dec. 31, 2018	Jan. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants Exercised		683,994	226,617
Warrants Outstanding		2,156,153	2,840,147
2017 Placement Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Issuance Date		2017-01
Term		7 years
Exercise Price Per Share		$ 3.17		$ 3.17
Warrants Exercised		90,642	1,591
Warrants Outstanding		1,618,890	1,709,532
2016 Placement Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Issuance Date		2016-08
Issuance Date		2016-09
Term	7 years	7 years
Exercise Price Per Share	$ 2.95	$ 2.95
Warrants Exercised		593,352	225,026
Warrants Outstanding		537,263	1,130,615