Condensed consolidating guarantor financial information - Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 02, 2017	Mar. 27, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	$ 90,940	$ 66,832
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(12,894)	(7,822)
Proceeds from sale of assets	6,332	1,251
Payments for businesses and intangibles acquired, net of cash acquired	(975,524)	0
Net cash used in investing activities from continuing operations	(982,086)	(6,571)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	1,194,500	0
Reduction in borrowings	(138,251)	(9)
Debt extinguishment, issuance and amendment fees	(19,114)	0
Net proceeds from share based compensation plans and the related tax impacts	(505)	3,180
Payments for contingent consideration	(79)	(61)
Dividends paid	(15,287)	(14,179)
Intercompany transactions	0	0
Intercompany dividends paid	0
Net cash provided by (used in) financing activities from continuing operations	1,021,264	(11,069)
Cash flows from discontinued operations:
Net cash used in operating activities	(266)	(126)
Net cash used in discontinued operations	(266)	(126)
Effect of exchange rate changes on cash and cash equivalents	15,488	5,126
Net increase in cash and cash equivalents	145,340	54,192
Cash and cash equivalents at the beginning of the period	543,789	338,366
Cash and cash equivalents at the end of the period	689,129	392,558
Reportable Legal Entities | Parent Company
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	(86,020)	(18,852)
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(155)	(5)
Proceeds from sale of assets	0	0
Payments for businesses and intangibles acquired, net of cash acquired	(975,524)
Net cash used in investing activities from continuing operations	(975,679)	(5)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	1,194,500
Reduction in borrowings	(138,251)	(9)
Debt extinguishment, issuance and amendment fees	(19,114)
Net proceeds from share based compensation plans and the related tax impacts	(505)	3,180
Payments for contingent consideration	0	0
Dividends paid	(15,287)	(14,179)
Intercompany transactions	179,151	32,371
Intercompany dividends paid	0
Net cash provided by (used in) financing activities from continuing operations	1,200,494	21,363
Cash flows from discontinued operations:
Net cash used in operating activities	(266)	(126)
Net cash used in discontinued operations	(266)	(126)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	138,529	2,380
Cash and cash equivalents at the beginning of the period	14,571	21,612
Cash and cash equivalents at the end of the period	153,100	23,992
Reportable Legal Entities | Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	158,343	25,624
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(2,206)	(3,470)
Proceeds from sale of assets	0	0
Payments for businesses and intangibles acquired, net of cash acquired	0
Net cash used in investing activities from continuing operations	(2,206)	(3,470)
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
Net proceeds from share based compensation plans and the related tax impacts	0	0
Payments for contingent consideration	(79)	(61)
Dividends paid	0	0
Intercompany transactions	(149,496)	(21,088)
Intercompany dividends paid	0
Net cash provided by (used in) financing activities from continuing operations	(149,575)	(21,149)
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	6,562	1,005
Cash and cash equivalents at the beginning of the period	1,031	0
Cash and cash equivalents at the end of the period	7,593	1,005
Reportable Legal Entities | Non-Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	80,535	60,060
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(10,533)	(4,347)
Proceeds from sale of assets	6,332	1,251
Payments for businesses and intangibles acquired, net of cash acquired	0
Net cash used in investing activities from continuing operations	(4,201)	(3,096)
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
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	(29,655)	(11,283)
Intercompany dividends paid	(61,918)
Net cash provided by (used in) financing activities from continuing operations	(91,573)	(11,283)
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	15,488	5,126
Net increase in cash and cash equivalents	249	50,807
Cash and cash equivalents at the beginning of the period	528,187	316,754
Cash and cash equivalents at the end of the period	528,436	$ 367,561
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	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
Cash and cash equivalents at the beginning of the period	0
Cash and cash equivalents at the end of the period	$ 0