Fair Value of Financial Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value (Detail) $ in Thousands	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
The Amended Loan Agreement
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Debt instrument, fair value	$ 25,300
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	48,658	$ 63,637
Fair Value, Measurements, Recurring | Level 1
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	46,815	23,638
Fair Value, Measurements, Recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	1,843	39,999
Fair Value, Measurements, Recurring | Level 3
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash equivalents	$ 0	$ 0
Measurement Input, Discount Rate
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Debt instrument, measurement input	0.115
Minimum | Measurement Input, Discount Rate
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Debt instrument, measurement input	0.105
Maximum | Measurement Input, Discount Rate
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Debt instrument, measurement input	0.125