Derivative instruments and hedging activities - Fair Values Of Derivative Instruments On Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative assets	$ 8,209	$ 9,369
Derivative liabilities	(2,872)	(1,483)
Derivatives designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative assets	8,009	8,974
Derivative liabilities	(2,440)	(853)
Derivatives designated as hedging instruments \| Foreign exchange contracts - ST forwards \| Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative assets	7,039	7,594
Derivatives designated as hedging instruments \| Foreign exchange contracts - ST forwards \| Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	(2,089)	(662)
Derivatives designated as hedging instruments \| Foreign exchange contracts - LT forwards \| Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets	970	1,380
Derivatives designated as hedging instruments \| Foreign exchange contracts - LT forwards \| Other long-term liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	(351)	(191)
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative assets	200	395
Derivative liabilities	(432)	(630)
Derivatives not designated as hedging instruments \| Foreign exchange contracts - ST forwards \| Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative assets	200	395
Derivatives not designated as hedging instruments \| Foreign exchange contracts - ST forwards \| Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ (432)	$ (630)

Fair value of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, not subject to a master netting arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

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- Definition

Fair value of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, not subject to a master netting arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313

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- Definition

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+ References

No definition available.

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