Fair Value of Financial Assets and Liabilities - Quantitative Information about Level 3 Fair Value Measurements on Recurring Basis (Detail) - Level 3 $ in Thousands	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	$ 0	$ 0
Liabilities, fair value	$ 27,484	$ 39,791
Minimum | Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration, liability, measurement input	0.068	0.068
Minimum | Probability of Meeting Earnout and Contingencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration, liability, measurement input	0.11	0.39
Maximum | Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration, liability, measurement input	0.103	0.103
Maximum | Probability of Meeting Earnout and Contingencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration, liability, measurement input	1	1
Weighted Average | Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration, liability, measurement input	0.098	0.095
Weighted Average | Probability of Meeting Earnout and Contingencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration, liability, measurement input	0.710	0.829