Fair Value Measurements - Summary of Assumptions Used to Estimate Fair Value of Contingent Payments (Detail) - Level 3 [Member]	9 Months Ended
	Sep. 30, 2020
Expected Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	1.137
Risk-free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	0.0013
Cost of Capital [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	0.30
Minimum [Member] | Discount for Lack of Marketability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	0.12
Minimum [Member] | Probability of Payment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	0.63
Minimum [Member] | Projected Year of Payment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	2020
Maximum [Member] | Discount for Lack of Marketability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	0.18
Maximum [Member] | Probability of Payment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	1.00
Maximum [Member] | Projected Year of Payment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	2022
Weighted Average [Member] | Expected Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	1.137
Weighted Average [Member] | Risk-free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	0.0013
Weighted Average [Member] | Cost of Capital [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	0.30
Weighted Average [Member] | Discount for Lack of Marketability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	0.15
Weighted Average [Member] | Probability of Payment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	0.91
Weighted Average [Member] | Projected Year of Payment [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assumptions used to estimate fair value of contingent payments	2020