Changes in accumulated other comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 03, 2021	Mar. 28, 2020
Accumulated Other Comprehensive Income [Roll Forward]
Beginning of Period	$ (488,428)	$ (350,933)
Other comprehensive income before reclassification	(7,195)	(60,594)
Amounts reclassified from accumulated other comprehensive income	5,023	1,267
Net current-period other comprehensive income	(2,172)	(59,327)
End of Period	(490,600)	(410,260)
Accumulated Other Comprehensive (income) Loss, Defined Benefit Plan, Tax	(90,000)	(45,500)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Tax	(8,800)	(15,300)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	4,300	(9,300)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax	(900)	3,100
Accumulated Translation Adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Beginning of Period	(49,961)	(105,705)
Other comprehensive income before reclassification	(10,614)	(48,916)
Amounts reclassified from accumulated other comprehensive income	0	0
Net current-period other comprehensive income	(10,614)	(48,916)
End of Period	(60,575)	(154,621)
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Beginning of Period	(400,919)	(228,336)
Other comprehensive income before reclassification	3,970	(14,808)
Amounts reclassified from accumulated other comprehensive income	0	0
Net current-period other comprehensive income	(3,970)	14,808
End of Period	(404,889)	(213,528)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Interest Rate Swap
Accumulated Other Comprehensive Income [Roll Forward]
Beginning of Period	(37,548)	(16,892)
Other comprehensive income before reclassification	7,389	(26,486)
Amounts reclassified from accumulated other comprehensive income	5,023	1,267
Net current-period other comprehensive income	12,412	(25,219)
End of Period	$ (25,136)	$ (42,111)