Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of decrease in the fair value of derivatives recognized in the income statement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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The net gain (loss) recognized in earnings during the reporting period representing the amount of the cash flow hedges' ineffectiveness.

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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Financial instruments - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017	Dec. 31, 2017
Spain, Italy, Portugal, and Greece
Derivatives Fair Value [Line Items]
Net revenues			$ 75,700,000	$ 64,500,000
Cash flow hedging
Derivatives Fair Value [Line Items]
Ineffectiveness related to derivatives	$ 0	$ 0	0	0
Foreign exchange contract \| Designated as Hedging Instrument \| Cash flow hedging
Derivatives Fair Value [Line Items]
Total notional amount for all open foreign currency forward contracts	113,800,000		113,800,000		$ 88,500,000
Foreign exchange contract \| Not Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Loss related to currency forward contracts	1,400,000	$ 2,300,000	700,000	$ 3,100,000
Total notional amount for all open foreign currency forward contracts	$ 110,500,000		$ 110,500,000		$ 110,600,000