Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Income Tax Disclosure [Abstract]
Reserves and liabilities	$ 35,258	$ 52,632
Loss carryforwards	37,850	53,175
Tax credit carryforwards	35,308	39,078
Employee benefits	10,197	12,720
Retirement benefits	6,086	14,907
Non-qualified stock options	7,470	10,937
Hedging activities	2,614	0
Other	3,105	3,940
Total deferred tax assets	137,888	187,389
Less valuation allowance	(27,118)	(45,601)
Total deferred tax assets, net of valuation allowance	110,770	141,788
Depreciation and amortization	(18)	(6,503)
Intangibles and amortization	(85,072)	(111,196)
Deferred costs	(3,697)	(5,668)
Hedging activities	0	(2,450)
Other	(6,874)	(3,156)
Total deferred tax liabilities	(95,661)	(128,973)
Net deferred tax assets (liabilities)	$ 15,109	$ 12,815