Acquisitions and Investments in Joint Ventures - Summary of Recording of Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Dec. 01, 2015	Jul. 31, 2015	Sep. 24, 2016	Sep. 26, 2015	Sep. 27, 2014	Apr. 01, 2014	Sep. 28, 2013
Business Acquisition [Line Items]
Goodwill			$ 231,385	$ 209,089	$ 208,233		$ 205,756
DMC [Member]
Business Acquisition [Line Items]
Current assets, net of cash and cash equivalents acquired	$ 41,326
Fixed assets	538
Goodwill	15,058
Other assets	20
Intangible assets	18,700
Current liabilities	(14,626)
Net assets acquired, less cash and cash equivalents	61,016
IMS Trading Corp [Member]
Business Acquisition [Line Items]
Current assets, net of cash and cash equivalents acquired		$ 20,773
Fixed assets		1,670
Goodwill		1,365	$ 1,400
Other assets		0
Intangible assets		4,510
Current liabilities		(5,100)
Net assets acquired, less cash and cash equivalents		23,218
Envincio, LLC [Member]
Business Acquisition [Line Items]
Current assets, net of cash and cash equivalents acquired						$ 6,650
Fixed assets						20
Goodwill						3,333
Intangible assets						11,450
Current liabilities						(1,170)
Net assets acquired, less cash and cash equivalents						$ 20,283
Amounts Previously Recognized as of Acquisition Date [Member] | DMC [Member]
Business Acquisition [Line Items]
Current assets, net of cash and cash equivalents acquired	41,170
Fixed assets	521
Goodwill	0
Other assets	33,810
Intangible assets	0
Current liabilities	(14,586)
Net assets acquired, less cash and cash equivalents	60,915
Amounts Previously Recognized as of Acquisition Date [Member] | IMS Trading Corp [Member]
Business Acquisition [Line Items]
Current assets, net of cash and cash equivalents acquired		20,458
Fixed assets		1,670
Goodwill		0
Other assets		5,356
Intangible assets		0
Current liabilities		(5,100)
Net assets acquired, less cash and cash equivalents		22,384
Measurement Period Adjustments [Member] | DMC [Member]
Measurement Period Adjustments
Current assets, net of cash and cash equivalents acquired	156
Fixed assets	17
Goodwill	15,058
Other assets	(33,790)
Other intangible assets, net	18,700
Current liabilities	(40)
Net assets acquired, less cash and cash equivalents	$ 101
Measurement Period Adjustments [Member] | IMS Trading Corp [Member]
Measurement Period Adjustments
Current assets, net of cash and cash equivalents acquired		315
Fixed assets		0
Goodwill		1,365
Other assets		(5,356)
Other intangible assets, net		4,510
Current liabilities		0
Net assets acquired, less cash and cash equivalents		$ 834