Shareholders' equity - Change in accumulated other comprehensive income, net of tax (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 29, 2020	Mar. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 2,979,320	$ 2,539,978
Amounts reclassified from accumulated other comprehensive income	1,369	1,188
Ending Balance	3,073,024	2,569,878
Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	735	807
Other comprehensive (loss) income before reclassifications	(3,760)	(434)
Amounts reclassified from accumulated other comprehensive income	(57)	(163)
Net current-period other comprehensive (loss) income	(3,817)	(597)
Ending Balance	(3,082)	210
Pension and Other Postretirement Benefit Plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(138,810)	(131,380)
Other comprehensive (loss) income before reclassifications	263	(122)
Amounts reclassified from accumulated other comprehensive income	1,426	1,351
Net current-period other comprehensive (loss) income	1,689	1,229
Ending Balance	(137,121)	(130,151)
Foreign Currency Translation Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(206,317)	(210,512)
Other comprehensive (loss) income before reclassifications	(18,199)	(236)
Amounts reclassified from accumulated other comprehensive income	0	0
Net current-period other comprehensive (loss) income	(18,199)	(236)
Ending Balance	(224,516)	(210,748)
Accumulated Other Comprehensive (Loss) Income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(344,392)	(341,085)
Other comprehensive (loss) income before reclassifications	(21,696)	(792)
Amounts reclassified from accumulated other comprehensive income	1,369	1,188
Net current-period other comprehensive (loss) income	(20,327)	396
Ending Balance	$ (364,719)	$ (340,689)

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount of increase (decrease) in other comprehensive income, after tax, from changes classified as other.

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Amount after tax of reclassification adjustments of other comprehensive income (loss).

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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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