Shareholders' equity - Accumulated other comprehensive income (loss) into income expense (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 27, 2020	Jun. 28, 2020	Mar. 29, 2020	Dec. 31, 2019	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of goods sold									$ 1,212,282	$ 1,186,357	$ 1,145,567
Income from continuing operations before taxes									357,732	339,903	219,628
Taxes (benefit) on income from continuing operations									21,931	(122,078)	23,196
Net of tax	$ 76,601	$ 116,605	$ 11,443	$ 131,152	$ 107,806	$ 228,929	$ 83,328	$ 41,918	335,801	461,981	196,432
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Impact on income from continuing operations, net of tax									7,699	4,247	3,716
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges | Foreign Exchange Forward
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of goods sold									2,354	(1,284)	(2,270)
Income from continuing operations before taxes									2,354	(1,284)	(2,270)
Taxes (benefit) on income from continuing operations									240	(150)	(163)
Net of tax									2,114	(1,134)	(2,107)
Reclassification out of Accumulated Other Comprehensive Income | Pension and Other Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income from continuing operations before taxes									7,286	7,012	7,556
Taxes (benefit) on income from continuing operations									1,701	1,631	1,733
Net of tax									5,585	5,381	5,823
Actuarial losses									7,253	6,930	7,305
Prior-service credits									$ 33	$ 82	$ 251