Fair Value of Financial Instruments - Significant Inputs Utilized in the Valuation of Letter Agreement Warrants (Detail) - Letter Agreement Warrants [Member]	Dec. 31, 2021	Dec. 31, 2020	Dec. 23, 2019	Sep. 26, 2019	Dec. 11, 2018	Jul. 30, 2018	Dec. 05, 2017
Expected Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Inputs utilized in the valuation of warrants			110.41	110.35	104.46	95.29	90.00
Risk-Free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Inputs utilized in the valuation of warrants			1.84	1.65	2.77	2.94	2.80
Minimum [Member] | Expected Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Inputs utilized in the valuation of warrants	82.68	120.53
Minimum [Member] | Risk-Free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Inputs utilized in the valuation of warrants	0.95	0.26
Maximum [Member] | Expected Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Inputs utilized in the valuation of warrants	142.86	142.07
Maximum [Member] | Risk-Free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Inputs utilized in the valuation of warrants	1.26	0.50
Weighted Average [Member] | Expected Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Inputs utilized in the valuation of warrants	128.13	128.16
Weighted Average [Member] | Risk-Free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Inputs utilized in the valuation of warrants	1.15	0.39