Condensed consolidating guarantor financial information - Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 25, 2016	Sep. 27, 2015
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Net cash (used in) provided by operating activities from continuing operations	$ 301,598	$ 176,760
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(35,912)	(45,566)
Proceeds from sale of assets	9,792	408
Payments for businesses and intangibles acquired, net of cash acquired	(14,040)	(63,451)
Investments in affiliates		0
Net cash used in investing activities from continuing operations	(40,160)	(108,609)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	671,700	288,100
Reduction in borrowings	(714,487)	(303,627)
Debt extinguishment, issuance and amendment fees	(8,958)	(9,017)
Net proceeds from share based compensation plans and the related tax impacts	7,647	4,815
Payments to noncontrolling interest shareholders	(464)	(833)
Payments for contingent consideration	(133)	(7,974)
Proceeds from issuance of shares		0
Payments for acquisition of noncontrolling interest	(9,231)	0
Dividends paid	(43,980)	(42,382)
Intercompany transactions	0	0
Intercompany dividends paid	0	0
Net cash used in financing activities from continuing operations	(97,906)	(70,918)
Cash flows from discontinued operations:
Net cash used in operating activities	(1,451)	(1,954)
Net cash used in discontinued operations	(1,451)	(1,954)
Effect of exchange rate changes on cash and cash equivalents	(988)	(22,052)
Net increase (decrease) in cash and cash equivalents	161,093	(26,773)
Cash and cash equivalents at the beginning of the period	338,366	303,236
Cash and cash equivalents at the end of the period	499,459	276,463
Reportable Legal Entities | Parent Company
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Net cash (used in) provided by operating activities from continuing operations	(72,542)	(124,131)
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(191)	(122)
Proceeds from sale of assets	5,607	408
Payments for businesses and intangibles acquired, net of cash acquired	0	0
Investments in affiliates		0
Net cash used in investing activities from continuing operations	5,416	286
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	665,000	288,100
Reduction in borrowings	(714,487)	(303,627)
Debt extinguishment, issuance and amendment fees	(8,958)	(9,017)
Net proceeds from share based compensation plans and the related tax impacts	7,647	4,815
Payments to noncontrolling interest shareholders	0	0
Payments for contingent consideration	0	0
Proceeds from issuance of shares		0
Payments for acquisition of noncontrolling interest	0
Dividends paid	(43,980)	(42,382)
Intercompany transactions	175,203	196,963
Intercompany dividends paid	0	0
Net cash used in financing activities from continuing operations	80,425	134,852
Cash flows from discontinued operations:
Net cash used in operating activities	(1,451)	(1,105)
Net cash used in discontinued operations	(1,451)	(1,105)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net increase (decrease) in cash and cash equivalents	11,848	9,902
Cash and cash equivalents at the beginning of the period	21,612	27,996
Cash and cash equivalents at the end of the period	33,460	37,898
Reportable Legal Entities | Guarantor Subsidiaries
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Net cash (used in) provided by operating activities from continuing operations	123,249	88,937
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(15,713)	(25,072)
Proceeds from sale of assets	49,571	0
Payments for businesses and intangibles acquired, net of cash acquired	(10,305)	(30,336)
Investments in affiliates		0
Net cash used in investing activities from continuing operations	23,553	(55,408)
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	0
Payments for contingent consideration	(133)	(7,974)
Proceeds from issuance of shares		121,850
Payments for acquisition of noncontrolling interest	0
Dividends paid	0	0
Intercompany transactions	(145,645)	(147,365)
Intercompany dividends paid	0	0
Net cash used in financing activities from continuing operations	(145,778)	(33,489)
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 (decrease) in cash and cash equivalents	1,024	40
Cash and cash equivalents at the beginning of the period	0	0
Cash and cash equivalents at the end of the period	1,024	40
Reportable Legal Entities | Non-Guarantor Subsidiaries
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Net cash (used in) provided by operating activities from continuing operations	253,166	214,314
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(20,008)	(20,372)
Proceeds from sale of assets	1,451	0
Payments for businesses and intangibles acquired, net of cash acquired	(50,572)	(33,115)
Investments in affiliates		(121,850)
Net cash used in investing activities from continuing operations	(69,129)	(175,337)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	6,700	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	(464)	(833)
Payments for contingent consideration	0	0
Proceeds from issuance of shares		0
Payments for acquisition of noncontrolling interest	(9,231)
Dividends paid	0	0
Intercompany transactions	(29,558)	(49,598)
Intercompany dividends paid	(2,275)	(2,360)
Net cash used in financing activities from continuing operations	(34,828)	(52,791)
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	(988)	(22,052)
Net increase (decrease) in cash and cash equivalents	148,221	(36,715)
Cash and cash equivalents at the beginning of the period	316,754	275,240
Cash and cash equivalents at the end of the period	464,975	238,525
Consolidation, Eliminations
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Net cash (used in) provided by operating activities from continuing operations	(2,275)	(2,360)
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	0	0
Proceeds from sale of assets	(46,837)	0
Payments for businesses and intangibles acquired, net of cash acquired	46,837	0
Investments in affiliates		121,850
Net cash used in investing activities from continuing operations	0	121,850
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	0
Payments for contingent consideration	0	0
Proceeds from issuance of shares		(121,850)
Payments for acquisition of noncontrolling interest	0
Dividends paid	0	0
Intercompany transactions	0	0
Intercompany dividends paid	2,275	2,360
Net cash used in financing activities from continuing operations	2,275	(119,490)
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 (decrease) 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