Accumulated other comprehensive income (loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 04, 2015
Accumulated Other Comprehensive Income Rollforward [Roll Forward]
Balance as of December 31, 2014	$ (429,321)
Current period other comprehensive income (loss) before reclassifications	(226,073)
Balance as of April 4, 2015	(655,394)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income Rollforward [Roll Forward]
Balance as of December 31, 2014	(428,505)
Current period other comprehensive income (loss) before reclassifications	(226,159)
Balance as of April 4, 2015	(654,664)
Pensions
Accumulated Other Comprehensive Income Rollforward [Roll Forward]
Balance as of December 31, 2014	(816)	[1]
Current period other comprehensive income (loss) before reclassifications	86	[1]
Balance as of April 4, 2015	$ (730)	[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, 2014).