Fair value measurement - Financial assets and liabilities carried at fair value measured on recurring basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments in marketable securities	$ 12,617	$ 10,926
Derivative assets	21,858	36,492
Derivative liabilities	35,995	1,387
Contingent consideration liabilities	36,633	219,908
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments in marketable securities	12,617	10,926
Derivative assets	0	0
Derivative liabilities	0	0
Contingent consideration liabilities	0	0
Significant Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments in marketable securities	0	0
Derivative assets	21,858	36,492
Derivative liabilities	35,995	1,387
Contingent consideration liabilities	0	0
Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments in marketable securities	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Contingent consideration liabilities	$ 36,633	$ 219,908