Financial instruments After tax (gain)/loss reclassified from accumulated other comprehensive income into income (Details) - Cash Flow Hedging - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives qualifying as hedges, net of tax	$ (803)	$ 73	$ (759)	$ 143
Foreign Currency Forward Contract
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives qualifying as hedges, net of tax	$ (803)	$ 73	$ (759)	$ 143

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

Name:	us-gaap_DerivativeInstrumentsGainLossRecognizedInOtherComprehensiveIncomeEffectivePortionNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration