Condensed consolidating guarantor financial information - Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 26, 2016	Jun. 28, 2015
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Net cash (used in) provided by operating activities from continuing operations	$ 181,488	$ 109,588
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(19,535)	(31,321)
Proceeds from sale of assets	3,985	0
Payments for businesses and intangibles acquired, net of cash acquired	(3,117)	(37,559)
Net cash used in investing activities from continuing operations	(18,667)	(68,880)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	665,000	288,100
Reduction in borrowings	(656,479)	(250,981)
Debt extinguishment, issuance and amendment fees	(8,182)	(8,746)
Net proceeds from share based compensation plans and the related tax impacts	6,593	4,843
Payments to noncontrolling interest shareholders	0	(832)
Payments for contingent consideration	(133)	(3,989)
Dividends paid	(28,998)	(28,234)
Intercompany transactions	0	0
Intercompany dividends paid		0
Net cash (used in) provided by financing activities from continuing operations	(22,199)	161
Cash flows from discontinued operations:
Net cash used in operating activities	(1,183)	(1,363)
Net cash used in discontinued operations	(1,183)	(1,363)
Effect of exchange rate changes on cash and cash equivalents	(1,315)	(17,732)
Net increase in cash and cash equivalents	138,124	21,774
Cash and cash equivalents at the beginning of the period	338,366	303,236
Cash and cash equivalents at the end of the period	476,490	325,010
Consolidation, Eliminations
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Net cash (used in) provided by operating activities from continuing operations	0	(2,360)
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	0	0
Proceeds from sale of assets	(17,908)
Payments for businesses and intangibles acquired, net of cash acquired	17,908	0
Net cash used in investing activities from continuing operations	0	0
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	0	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 to noncontrolling interest shareholders		0
Payments for contingent consideration	0	0
Dividends paid	0	0
Intercompany transactions	0	0
Intercompany dividends paid		2,360
Net cash (used in) provided by financing activities from continuing operations	0	2,360
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	0	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 | Reportable Legal Entities
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Net cash (used in) provided by operating activities from continuing operations	(29,648)	(92,490)
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(146)	(108)
Proceeds from sale of assets	0
Payments for businesses and intangibles acquired, net of cash acquired	0	0
Net cash used in investing activities from continuing operations	(146)	(108)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	665,000	288,100
Reduction in borrowings	(656,479)	(250,981)
Debt extinguishment, issuance and amendment fees	(8,182)	(8,746)
Net proceeds from share based compensation plans and the related tax impacts	6,593	4,843
Payments to noncontrolling interest shareholders		0
Payments for contingent consideration	0	0
Dividends paid	(28,998)	(28,234)
Intercompany transactions	81,640	86,197
Intercompany dividends paid		0
Net cash (used in) provided by financing activities from continuing operations	59,574	91,179
Cash flows from discontinued operations:
Net cash used in operating activities	(1,183)	(514)
Net cash used in discontinued operations	(1,183)	(514)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net increase in cash and cash equivalents	28,597	(1,933)
Cash and cash equivalents at the beginning of the period	21,612	27,996
Cash and cash equivalents at the end of the period	50,209	26,063
Guarantor Subsidiaries | Reportable Legal Entities
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Net cash (used in) provided by operating activities from continuing operations	69,875	63,718
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(9,947)	(17,339)
Proceeds from sale of assets	20,642
Payments for businesses and intangibles acquired, net of cash acquired	0	(4,348)
Net cash used in investing activities from continuing operations	10,695	(21,687)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	0	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 to noncontrolling interest shareholders		0
Payments for contingent consideration	(133)	(3,989)
Dividends paid	0	0
Intercompany transactions	(79,348)	(37,744)
Intercompany dividends paid		0
Net cash (used in) provided by financing activities from continuing operations	(79,481)	(41,733)
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	1,089	298
Cash and cash equivalents at the beginning of the period	0	0
Cash and cash equivalents at the end of the period	1,089	298
Non-Guarantor Subsidiaries | Reportable Legal Entities
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Net cash (used in) provided by operating activities from continuing operations	141,261	140,720
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(9,442)	(13,874)
Proceeds from sale of assets	1,251
Payments for businesses and intangibles acquired, net of cash acquired	(21,025)	(33,211)
Net cash used in investing activities from continuing operations	(29,216)	(47,085)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	0	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 to noncontrolling interest shareholders		(832)
Payments for contingent consideration	0	0
Dividends paid	0	0
Intercompany transactions	(2,292)	(48,453)
Intercompany dividends paid		(2,360)
Net cash (used in) provided by financing activities from continuing operations	(2,292)	(51,645)
Cash flows from discontinued operations:
Net cash used in operating activities	0	(849)
Net cash used in discontinued operations	0	(849)
Effect of exchange rate changes on cash and cash equivalents	(1,315)	(17,732)
Net increase in cash and cash equivalents	108,438	23,409
Cash and cash equivalents at the beginning of the period	316,754	275,240
Cash and cash equivalents at the end of the period	$ 425,192	$ 298,649