Changes in accumulated other comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Oct. 01, 2022	Sep. 30, 2023	Oct. 01, 2022
Accumulated Other Comprehensive Income [Roll Forward]
Beginning of Period			$ (278,472)	$ (359,084)
Other comprehensive income before reclassification			14,990	(102,421)
Amounts reclassified from accumulated other comprehensive income			(22,376)	7,646
Net current-period other comprehensive income			(7,386)	(94,775)
End of Period	$ (285,858)	$ (453,859)	(285,858)	(453,859)
Accumulated Other Comprehensive (income) Loss, Defined Benefit Plan, Tax	(1,500)	(32,600)	(1,500)	(32,600)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Tax	16,100	17,900	16,100	17,900
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax			500	6,900
Unrealized gain on interest rate swap, tax	7	8,574	(731)	22,389
Other Comprehensive Income (Loss), Unrealized Gain (loss) Certain Investments, Tax				(400)
Accumulated Translation Adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Beginning of Period			(205,345)	(97,654)
Other comprehensive income before reclassification			(4,751)	(201,176)
Amounts reclassified from accumulated other comprehensive income			0	0
Net current-period other comprehensive income			(4,751)	(201,176)
End of Period	(210,096)	(298,830)	(210,096)	(298,830)
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Beginning of Period			(121,701)	(249,696)
Other comprehensive income before reclassification			2,131	(44,127)
Amounts reclassified from accumulated other comprehensive income			1,587	0
Net current-period other comprehensive income			(544)	44,127
End of Period	(122,245)	(205,569)	(122,245)	(205,569)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Interest Rate Swap
Accumulated Other Comprehensive Income [Roll Forward]
Beginning of Period			48,574	(13,064)
Other comprehensive income before reclassification			21,872	55,958
Amounts reclassified from accumulated other comprehensive income			(23,963)	7,646
Net current-period other comprehensive income			(2,091)	63,604
End of Period	46,483	50,540	46,483	50,540
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent
Accumulated Other Comprehensive Income [Roll Forward]
Beginning of Period			0	1,330
Other comprehensive income before reclassification			0	(1,330)
Amounts reclassified from accumulated other comprehensive income			0	0
Net current-period other comprehensive income			0	(1,330)
End of Period	$ 0	$ 0	$ 0	$ 0