Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 29, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Reserves and liabilities	$ 52,632	$ 54,370
Loss carryforwards	53,175	51,760
Tax credit carryforwards	39,078	34,836
Employee benefits	12,720	13,853
Retirement benefits	14,907	22,703
Non-qualified stock options	10,937	13,760
Hedging activities	0	3,350
Other	3,940	1,003
Total deferred tax assets	187,389	195,635
Less valuation allowance	(45,601)	(43,503)
Total deferred tax assets, net of valuation allowance	141,788	152,132
Depreciation and amortization	(6,503)	(7,456)
Intangibles and amortization	(111,196)	(116,620)
Deferred costs	(5,668)	(3,907)
Hedging activities	(2,450)	0
Other	(3,156)	(2,684)
Total deferred tax liabilities	(128,973)	(130,667)
Net deferred tax assets (liabilities)	$ 12,815	$ 21,465