Condensed consolidating guarantor financial information - Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	$ 86,848	$ 90,940
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(15,747)	(12,894)
Proceeds from sale of assets and investments	0	6,332
Payments for businesses and intangibles acquired, net of cash acquired	(3,684)	(975,524)
Net cash used in investing activities from continuing operations	(19,431)	(982,086)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	0	1,194,500
Reduction in borrowings	(18,500)	(138,251)
Debt extinguishment, issuance and amendment fees	(74)	(19,114)
Net proceeds from share based compensation plans and the related tax impacts	1,400	(505)
Payments for contingent consideration	(91)	(79)
Dividends paid	(15,447)	(15,287)
Intercompany transactions	0	0
Intercompany dividends paid		0
Net cash provided by (used in) financing activities from continuing operations	(32,712)	1,021,264
Cash flows from discontinued operations:
Net cash used in operating activities	(206)	(266)
Net cash used in discontinued operations	(206)	(266)
Effect of exchange rate changes on cash and cash equivalents	10,815	15,488
Net increase in cash and cash equivalents	45,314	145,340
Cash and cash equivalents at the beginning of the period	333,558	543,789
Cash and cash equivalents at the end of the period	378,872	689,129
Eliminations
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations		(61,918)
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment		0
Proceeds from sale of assets and investments		0
Payments for businesses and intangibles acquired, net of cash acquired		0
Net cash used in investing activities from continuing operations		0
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings		0
Reduction in borrowings		0
Debt extinguishment, issuance and amendment fees		0
Net proceeds from share based compensation plans and the related tax impacts		0
Payments for contingent consideration		0
Dividends paid		0
Intercompany transactions		0
Intercompany dividends paid		61,918
Net cash provided by (used in) financing activities from continuing operations		61,918
Cash flows from discontinued operations:
Net cash used in operating activities		0
Net cash used in discontinued operations		0
Effect of exchange rate changes on cash and cash equivalents		0
Net increase in cash and cash equivalents		0
Cash and cash equivalents at the beginning of the period	0	0
Cash and cash equivalents at the end of the period	0	0
Parent Company
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	(108,377)	(86,020)
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(159)	(155)
Proceeds from sale of assets and investments		0
Payments for businesses and intangibles acquired, net of cash acquired	0	(975,524)
Net cash used in investing activities from continuing operations	(159)	(975,679)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings		1,194,500
Reduction in borrowings	(18,500)	(138,251)
Debt extinguishment, issuance and amendment fees	(74)	(19,114)
Net proceeds from share based compensation plans and the related tax impacts	1,400	(505)
Payments for contingent consideration	0	0
Dividends paid	(15,447)	(15,287)
Intercompany transactions	131,967	179,151
Intercompany dividends paid		0
Net cash provided by (used in) financing activities from continuing operations	99,346	1,200,494
Cash flows from discontinued operations:
Net cash used in operating activities	(206)	(266)
Net cash used in discontinued operations	(206)	(266)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	(9,396)	138,529
Cash and cash equivalents at the beginning of the period	37,803	14,571
Cash and cash equivalents at the end of the period	28,407	153,100
Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	134,198	158,343
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(5,015)	(2,206)
Proceeds from sale of assets and investments		0
Payments for businesses and intangibles acquired, net of cash acquired	0	0
Net cash used in investing activities from continuing operations	(5,015)	(2,206)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings		0
Reduction in borrowings	0	0
Debt extinguishment, issuance and amendment fees	0	0
Net proceeds from share based compensation plans and the related tax impacts	0	0
Payments for contingent consideration	(91)	(79)
Dividends paid	0	0
Intercompany transactions	(127,825)	(149,496)
Intercompany dividends paid		0
Net cash provided by (used in) financing activities from continuing operations	(127,916)	(149,575)
Cash flows from discontinued operations:
Net cash used in operating activities	0	0
Net cash used in discontinued operations	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	1,267	6,562
Cash and cash equivalents at the beginning of the period	8,933	1,031
Cash and cash equivalents at the end of the period	10,200	7,593
Non-Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	61,027	80,535
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(10,573)	(10,533)
Proceeds from sale of assets and investments		6,332
Payments for businesses and intangibles acquired, net of cash acquired	(3,684)	0
Net cash used in investing activities from continuing operations	(14,257)	(4,201)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings		0
Reduction in borrowings	0	0
Debt extinguishment, issuance and amendment fees	0	0
Net proceeds from share based compensation plans and the related tax impacts	0	0
Payments for contingent consideration	0	0
Dividends paid	0	0
Intercompany transactions	(4,142)	(29,655)
Intercompany dividends paid		(61,918)
Net cash provided by (used in) financing activities from continuing operations	(4,142)	(91,573)
Cash flows from discontinued operations:
Net cash used in operating activities	0	0
Net cash used in discontinued operations	0	0
Effect of exchange rate changes on cash and cash equivalents	10,815	15,488
Net increase in cash and cash equivalents	53,443	249
Cash and cash equivalents at the beginning of the period	286,822	528,187
Cash and cash equivalents at the end of the period	$ 340,265	$ 528,436