Derivative instruments and hedging activities - Effect Of Derivative Instruments On Consolidated Statements Of Income (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivatives Designated As Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in OCI on Derivative	$ (9,531)	$ 1,627	$ (10,128)	$ 1,359
Gain or (Loss) Reclassified from Accumulated OCI into Income	(380)	3,003	2,429	7,312
Derivatives Designated As Hedging Instruments \| Foreign Exchange Forward \| Net Sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in OCI on Derivative	(12,524)	6,736	(6,800)	7,186
Gain or (Loss) Reclassified from Accumulated OCI into Income	334	3,291	5,594	7,687
Derivatives Designated As Hedging Instruments \| Foreign Exchange Forward \| Cost of Sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in OCI on Derivative	1,849	(2,946)	(1,898)	(3,386)
Gain or (Loss) Reclassified from Accumulated OCI into Income	(448)	(176)	(1,817)	(217)
Derivatives Designated As Hedging Instruments \| Foreign Exchange Forward \| Operating Expenses
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in OCI on Derivative	1,144	(2,163)	(1,430)	(2,441)
Gain or (Loss) Reclassified from Accumulated OCI into Income	(266)	(112)	(1,348)	(158)
Derivatives Not Designated As Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	(267)	287	(163)	(82)
Derivatives Not Designated As Hedging Instruments \| Foreign Exchange Forward
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ (267)	$ 287	$ (163)	$ (82)

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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Amount, before tax and reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness.

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Amount, before tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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