Fair value measurement - Financial assets and liabilities carried at fair value measured on recurring basis (Details) - USD ($) $ in Thousands	Jun. 27, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments in marketable securities	$ 14,287	$ 12,617
Derivative assets	21,905	21,858
Derivative liabilities	22,985	35,995
Contingent consideration liabilities	13,974	36,633
Quoted prices in active markets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments in marketable securities	14,287	12,617
Derivative assets	0	0
Derivative liabilities	0	0
Contingent consideration liabilities	0	0
Significant other observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments in marketable securities	0	0
Derivative assets	21,905	21,858
Derivative liabilities	22,985	35,995
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	$ 13,974	$ 36,633