Condensed consolidating guarantor financial information - Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended		9 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Sep. 27, 2015
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	$ 157,284	$ 181,584
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(56,107)	(38,004)
Proceeds from sale of assets and investments	1,178	0
Payments for businesses and intangibles acquired, net of cash acquired	(1,025)	(22,450)
Net interest proceeds on swaps designated as net investment hedges	8,330		$ 0
Net cash used in investing activities from continuing operations	(47,624)	(60,454)
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	25,000	0
Reduction in borrowings	(52,500)	(18,500)
Debt extinguishment, issuance and amendment fees	(4,703)	(188)
Net proceeds from share based compensation plans and the related tax impacts	7,829	9,800
Payments for contingent consideration	(111,928)	(62,574)
Dividends paid	(31,347)	(30,938)
Intercompany transactions	0	0
Intercompany dividends paid	0	0
Net cash used in financing activities from continuing operations	(167,649)	(102,400)
Cash flows from discontinued operations:
Net cash provided by (used in) operating activities	2,799	(464)
Net cash provided by (used in) discontinued operations	2,799	(464)
Effect of exchange rate changes on cash and cash equivalents	1,925	(5,520)
Net (decrease) increase in cash and cash equivalents	(53,265)	12,746
Cash and cash equivalents at the beginning of the period	357,161	333,558
Cash and cash equivalents at the end of the period	303,896	346,304
Eliminations
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	(92,455)	(70,373)
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	0	0
Proceeds from sale of assets and investments	(2,362)	(22,944)
Payments for businesses and intangibles acquired, net of cash acquired	0	0
Net interest proceeds on swaps designated as net investment hedges	0
Net cash used in investing activities from continuing operations	(2,362)	(22,944)
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	2,362	22,944
Intercompany dividends paid	92,455	70,373
Net cash used in financing activities from continuing operations	94,817	93,317
Cash flows from discontinued operations:
Net cash provided by (used in) operating activities	0	0
Net cash provided by (used in) discontinued operations	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) 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
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	(60,841)	(165,764)
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(327)	(795)
Proceeds from sale of assets and investments	2,362	22,944
Payments for businesses and intangibles acquired, net of cash acquired	0	0
Net interest proceeds on swaps designated as net investment hedges	8,330
Net cash used in investing activities from continuing operations	10,365	22,149
Cash flows from financing activities of continuing operations:
Proceeds from new borrowings	25,000
Reduction in borrowings	(52,500)	(18,500)
Debt extinguishment, issuance and amendment fees	(4,703)	(188)
Net proceeds from share based compensation plans and the related tax impacts	7,829	9,800
Payments for contingent consideration	0	0
Dividends paid	(31,347)	(30,938)
Intercompany transactions	83,135	196,888
Intercompany dividends paid	0	0
Net cash used in financing activities from continuing operations	27,414	157,062
Cash flows from discontinued operations:
Net cash provided by (used in) operating activities	3,430	(464)
Net cash provided by (used in) discontinued operations	3,430	(464)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	(19,632)	12,983
Cash and cash equivalents at the beginning of the period	49,523	37,803
Cash and cash equivalents at the end of the period	29,891	50,786
Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	180,717	254,769
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(37,981)	(16,602)
Proceeds from sale of assets and investments	1,178	0
Payments for businesses and intangibles acquired, net of cash acquired	(1,025)	0
Net interest proceeds on swaps designated as net investment hedges	0
Net cash used in investing activities from continuing operations	(37,828)	(16,602)
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	(15,044)	(170)
Dividends paid	0	0
Intercompany transactions	(126,062)	(234,304)
Intercompany dividends paid	0	0
Net cash used in financing activities from continuing operations	(141,106)	(234,474)
Cash flows from discontinued operations:
Net cash provided by (used in) operating activities	0	0
Net cash provided by (used in) discontinued operations	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	1,783	3,693
Cash and cash equivalents at the beginning of the period	1,757	8,933
Cash and cash equivalents at the end of the period	3,540	12,626
Non-Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash (used in) provided by operating activities from continuing operations	129,863	162,952
Cash flows from investing activities of continuing operations:
Expenditures for property, plant and equipment	(17,799)	(20,607)
Proceeds from sale of assets and investments	0	0
Payments for businesses and intangibles acquired, net of cash acquired	0	(22,450)
Net interest proceeds on swaps designated as net investment hedges	0
Net cash used in investing activities from continuing operations	(17,799)	(43,057)
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	(96,884)	(62,404)
Dividends paid	0	0
Intercompany transactions	40,565	14,472
Intercompany dividends paid	(92,455)	(70,373)
Net cash used in financing activities from continuing operations	(148,774)	(118,305)
Cash flows from discontinued operations:
Net cash provided by (used in) operating activities	(631)	0
Net cash provided by (used in) discontinued operations	(631)	0
Effect of exchange rate changes on cash and cash equivalents	1,925	(5,520)
Net (decrease) increase in cash and cash equivalents	(35,416)	(3,930)
Cash and cash equivalents at the beginning of the period	305,881	286,822
Cash and cash equivalents at the end of the period	$ 270,465	$ 282,892