Basis of presentation and consolidation and significant accounting policies - Summary of Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Detail) $ in Thousands	Sep. 30, 2021 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Investments with Readily Determinable Fair Value	$ 20,070
Fair value input level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Investments with Readily Determinable Fair Value	$ 20,070