Consolidating Condensed Financial Information of Guarantor Subsidiaries - Consolidating Condensed Statement of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 24, 2016	Sep. 26, 2015	Sep. 27, 2014
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	$ 151,426	$ 87,449	$ 126,467
Additions to property, plant and equipment	(27,622)	(22,030)	(17,173)
Payments to acquire companies, net of expenses	(69,001)	(38,384)	(20,282)
Proceeds from disposal of land, buildings, etc.	3,911	0	8,737
Change in restricted cash and cash equivalents.	2,247	1,126	(14,283)
Maturities of short term investments	0	9,997	17,820
Investment in short-term investments	0	(17)	(10,000)
Other investing activities	(730)	(546)	0
Intercompany investing activities	0	0	0
Net cash used in investing activities	(91,195)	(49,854)	(35,181)
Repayments on revolving line of credit	(419,000)	(312,000)	(301,000)
Borrowings on revolving line of credit	419,000	312,000	278,000
Repayments of long-term debt	(400,307)	(50,289)	(367)
Issuance of long-term debt	400,000	0	0
Proceeds from issuance of common stock	324	200	1,165
Excess tax benefits from stock-based awards	6,869	2,154	498
Repurchase of common stock	(10,873)	(18,497)	(2,332)
Payments of contingent consideration	(2,026)	0	0
Payment of deferred financing costs	(7,560)	(258)	(3,090)
Distribution to parent	0	0	0
Distribution to noncontrolling interest	(592)	(1,680)	(633)
Intercompany financing activities	0	0	0
Net cash used by financing activities	(14,165)	(68,370)	(27,759)
Effect of exchange rates on cash	(668)	(317)	(7)
Net increase (decrease) in cash and cash equivalents	45,398	(31,092)	63,520
Cash and cash equivalents at beginning of year	47,584	78,676	15,156
Cash and cash equivalents at end of year	92,982	47,584	78,676
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	(4,883)	(6,719)	(2,534)
Additions to property, plant and equipment	0	0	0
Payments to acquire companies, net of expenses	0	0	0
Proceeds from disposal of land, buildings, etc.	0		0
Change in restricted cash and cash equivalents.	0	0	0
Maturities of short term investments	0	0	0
Investment in short-term investments	0	0	0
Other investing activities	0	0
Intercompany investing activities	130,183	101,752	111,652
Net cash used in investing activities	130,183	101,752	111,652
Repayments on revolving line of credit	0	0	0
Borrowings on revolving line of credit	0	0	0
Repayments of long-term debt	0	0	0
Issuance of long-term debt
Proceeds from issuance of common stock	0	0	0
Excess tax benefits from stock-based awards	0	0	0
Repurchase of common stock	0	0	0
Payments of contingent consideration
Payment of deferred financing costs	0	0	0
Distribution to parent	4,883	6,719	2,534
Distribution to noncontrolling interest	0	0	0
Intercompany financing activities	(130,183)	(101,752)	(111,652)
Net cash used by financing activities	(125,300)	(95,033)	(109,118)
Effect of exchange rates on cash	0	0	0
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of year	0	0	0
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	3,514	(16,823)	(4,139)
Additions to property, plant and equipment	(4,513)	(2,721)	(6,721)
Payments to acquire companies, net of expenses	(69,001)	(38,384)	0
Proceeds from disposal of land, buildings, etc.	0		0
Change in restricted cash and cash equivalents.	2,247	1,126	(14,283)
Maturities of short term investments	0	9,997	17,820
Investment in short-term investments	0	(17)	(10,000)
Other investing activities	(730)	(546)
Intercompany investing activities	(83)	(15,789)	(6,726)
Net cash used in investing activities	(72,080)	(46,334)	(19,910)
Repayments on revolving line of credit	(419,000)	(312,000)	(301,000)
Borrowings on revolving line of credit	419,000	312,000	278,000
Repayments of long-term debt	(400,286)	(50,262)	(243)
Issuance of long-term debt	400,000
Proceeds from issuance of common stock	324	200	1,165
Excess tax benefits from stock-based awards	6,869	2,154	498
Repurchase of common stock	(10,873)	(18,497)	(2,332)
Payments of contingent consideration
Payment of deferred financing costs	(7,560)	(258)	(3,090)
Distribution to parent	0	0	0
Distribution to noncontrolling interest	0	0	0
Intercompany financing activities	127,436	103,326	109,057
Net cash used by financing activities	115,910	36,663	82,055
Effect of exchange rates on cash	(1,466)	(697)	27
Net increase (decrease) in cash and cash equivalents	45,878	(27,191)	58,033
Cash and cash equivalents at beginning of year	36,280	63,471	5,438
Cash and cash equivalents at end of year	82,158	36,280	63,471
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	2,654	7,372	7,420
Additions to property, plant and equipment	(717)	(405)	(1,027)
Payments to acquire companies, net of expenses	0	0	0
Proceeds from disposal of land, buildings, etc.	0		0
Change in restricted cash and cash equivalents.	0	0	0
Maturities of short term investments	0	0	0
Investment in short-term investments	0	0	0
Other investing activities	0	0
Intercompany investing activities	0	0	0
Net cash used in investing activities	(717)	(405)	(1,027)
Repayments on revolving line of credit	0	0	0
Borrowings on revolving line of credit	0	0	0
Repayments of long-term debt	0	0	0
Issuance of long-term debt
Proceeds from issuance of common stock	0	0	0
Excess tax benefits from stock-based awards	0	0	0
Repurchase of common stock	0	0	0
Payments of contingent consideration
Payment of deferred financing costs	0	0	0
Distribution to parent	(4,883)	(6,719)	(2,534)
Distribution to noncontrolling interest	(592)	(1,680)	(633)
Intercompany financing activities	2,747	(1,574)	2,595
Net cash used by financing activities	(2,728)	(9,973)	(572)
Effect of exchange rates on cash	464	222	(18)
Net increase (decrease) in cash and cash equivalents	(327)	(2,784)	5,803
Cash and cash equivalents at beginning of year	10,022	12,806	7,003
Cash and cash equivalents at end of year	9,695	10,022	12,806
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	150,141	103,619	125,720
Additions to property, plant and equipment	(22,392)	(18,904)	(9,425)
Payments to acquire companies, net of expenses	0	0	(20,282)
Proceeds from disposal of land, buildings, etc.	3,911		8,737
Change in restricted cash and cash equivalents.	0	0	0
Maturities of short term investments	0	0	0
Investment in short-term investments	0	0	0
Other investing activities	0	0
Intercompany investing activities	(130,100)	(85,963)	(104,926)
Net cash used in investing activities	(148,581)	(104,867)	(125,896)
Repayments on revolving line of credit	0	0	0
Borrowings on revolving line of credit	0	0	0
Repayments of long-term debt	(21)	(27)	(124)
Issuance of long-term debt
Proceeds from issuance of common stock	0	0	0
Excess tax benefits from stock-based awards	0	0	0
Repurchase of common stock	0	0	0
Payments of contingent consideration	(2,026)
Payment of deferred financing costs	0	0	0
Distribution to parent	0	0	0
Distribution to noncontrolling interest	0	0	0
Intercompany financing activities	0	0	0
Net cash used by financing activities	(2,047)	(27)	(124)
Effect of exchange rates on cash	334	158	(16)
Net increase (decrease) in cash and cash equivalents	(153)	(1,117)	(316)
Cash and cash equivalents at beginning of year	1,282	2,399	2,715
Cash and cash equivalents at end of year	$ 1,129	$ 1,282	$ 2,399