Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 29, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Reserves and liabilities	$ 49,832	$ 53,119
Loss carryforwards	53,175	51,760
Tax credit carryforwards	40,440	34,836
Employee benefits	12,720	13,853
Retirement benefits	14,907	22,703
Non-qualified stock options	10,937	13,571
Hedging activities	0	3,350
Other	3,940	1,003
Total deferred tax assets	185,951	194,195
Less valuation allowance	(45,601)	(42,976)
Total deferred tax assets, net of valuation allowance	140,350	151,219
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)	(1,625)
Total deferred tax liabilities	(128,973)	(129,608)
Net deferred tax assets (liabilities)	$ 11,377	$ 21,611