Composition Of Certain Financial Statement Captions (Schedule Of Accounts Receivable) (Details) - USD ($) $ in Thousands	Sep. 24, 2021	Sep. 25, 2020
Composition Of Certain Financial Statement Captions [Abstract]
Trade accounts receivable	$ 160,112	$ 147,618
Accounts receivable from patent administration program partners	81,241	48,630
Contract with Customer, Asset, after Allowance for Credit Loss, Current	182,524	161,357
Accounts receivable, gross and contract assets, gross	423,877	357,605
Accounts Receivable And Contract With Customer, Asset, Allowance For Credit Loss, Current	(8,952)	(15,908)
Total accounts receivable and contract assets, net	$ 414,925	$ 341,697