Fair value measurement - financial assets and liabilities carried at fair value measured on recurring basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments in marketable securities	$ 10,926	$ 8,671
Derivative assets	36,492	16,050
Derivative liabilities	1,387	8,581
Contingent consideration liabilities	219,908	304,248
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	10,926	8,671
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	36,492	16,050
Derivative liabilities	1,387	8,581
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	$ 219,908	$ 304,248