Accumulated other comprehensive income (loss) (Details) $ in Thousands	9 Months Ended
	Oct. 01, 2016 USD ($)
Accumulated Other Comprehensive Income Rollforward [Roll Forward]
Balance as of December 31, 2015	$ 4,860,863
Balance as of October 1, 2016	5,672,688
Foreign currency translation adjustments [Member]
Accumulated Other Comprehensive Income Rollforward [Roll Forward]
Balance as of December 31, 2015	(788,652)
Current period other comprehensive income (loss) before reclassifications	89,458
Balance as of October 1, 2016	(699,194)
Pensions [Member]
Accumulated Other Comprehensive Income Rollforward [Roll Forward]
Balance as of December 31, 2015	(4,916)
Current period other comprehensive income (loss) before reclassifications	(10)
Balance as of October 1, 2016	(4,926)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income Rollforward [Roll Forward]
Balance as of December 31, 2015	(793,568)
Current period other comprehensive income (loss) before reclassifications	89,448
Balance as of October 1, 2016	$ (704,120)