Shareholders' equity - accumulated other comprehensive income (loss) into income expense (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of goods sold									$ 1,063,941	$ 974,501	$ 871,827
Income from continuing operations before taxes									219,628	284,911	245,725
Taxes on income from continuing operations									(23,196)	(129,648)	(8,074)
Income from continuing operations	$ 87,513	$ 56,540	$ (2,552)	$ 54,931	$ (42,847)	$ 79,398	$ 78,363	$ 40,349	196,432	155,263	237,651
Interest expense									103,020	82,546	54,941
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Impact on income from continuing operations, net of tax									1,193	4,502	8,013
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges | Foreign Exchange Forward
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of goods sold									(2,270)	(95)	4,511
Income from continuing operations before taxes									(2,270)	(95)	4,511
Taxes on income from continuing operations									163	84	(1,010)
Income from continuing operations									(2,107)	(11)	3,501
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges | Cross Currency Interest Rate Contract
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income from continuing operations before taxes									(3,277)	0	0
Taxes on income from continuing operations									754	0	0
Income from continuing operations									(2,523)	0	0
Interest expense									(3,277)	0	0
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									7,556	7,009	7,021
Taxes on income from continuing operations									(1,733)	(2,496)	(2,509)
Income from continuing operations									5,823	4,513	4,512
Actuarial losses									7,305	6,904	6,965
Prior-service credits									$ 251	$ 105	$ 56