Accumulated other comprehensive income (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 28, 2014
Accumulated Other Comprehensive Income Rollforward [Roll Forward]
Balance as of December 31, 2013	$ 178,689
Current period other comprehensive (loss) income before reclassifications	(43,310)
Amounts reclassified from accumulated other comprehensive (loss) income	0
Balance as of June 28, 2014	135,379
Foreign currency translation adjustments
Accumulated Other Comprehensive Income Rollforward [Roll Forward]
Balance as of December 31, 2013	178,846
Current period other comprehensive (loss) income before reclassifications	(43,314)
Amounts reclassified from accumulated other comprehensive (loss) income	0
Balance as of June 28, 2014	135,532
Pensions
Accumulated Other Comprehensive Income Rollforward [Roll Forward]
Balance as of December 31, 2013	(157)	[1]
Current period other comprehensive (loss) income before reclassifications	4	[1]
Amounts reclassified from accumulated other comprehensive (loss) income	0	[1]
Balance as of June 28, 2014	$ (153)	[1]

[1] This accumulated other comprehensive income (loss) component is included in the computation of net periodic pension cost (refer to Note 13 to the consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2013).