Warrants - Schedule of Key Terms of Placement Warrants (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants Exercised		683,994
Warrants Outstanding	2,156,153	2,156,153
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
Warrants Exercised		90,642
Warrants Outstanding	1,618,890	1,618,890
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
Exercise Price Per Share	$ 2.95
Warrants Exercised		593,352
Warrants Outstanding	537,263	537,263