Shareholders' equity - Change in accumulated other comprehensive income, net of tax (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2021	Sep. 27, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 3,336,457	$ 2,979,320
Other comprehensive income (loss) before reclassifications	(33,139)	15,499
Amounts reclassified from accumulated other comprehensive income	5,495	5,201
Net current-period other comprehensive income (loss)	(27,644)	20,700
Ending Balance	3,657,872	3,236,203
Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(482)	735
Other comprehensive income (loss) before reclassifications	(77)	(4,479)
Amounts reclassified from accumulated other comprehensive income	1,163	1,021
Net current-period other comprehensive income (loss)	1,086	(3,458)
Ending Balance	604	(2,723)
Pension and Other Postretirement Benefit Plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(150,257)	(138,810)
Other comprehensive income (loss) before reclassifications	245	(109)
Amounts reclassified from accumulated other comprehensive income	4,332	4,180
Net current-period other comprehensive income (loss)	4,577	4,071
Ending Balance	(145,680)	(134,739)
Foreign Currency Translation Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(146,559)	(206,317)
Other comprehensive income (loss) before reclassifications	(33,307)	20,087
Amounts reclassified from accumulated other comprehensive income	0	0
Net current-period other comprehensive income (loss)	(33,307)	20,087
Ending Balance	(179,866)	(186,230)
Accumulated Other Comprehensive (Loss) Income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(297,298)	(344,392)
Ending Balance	$ (324,942)	$ (323,692)