Income Taxes (Reconciliation Of Federal Statutory Tax Rate To Our Effective Tax Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2016	Sep. 25, 2015	Sep. 26, 2014	Sep. 27, 2013
Income Tax Disclosure [Abstract]
Federal statutory rate	35.00%	35.00%	35.00%
State income taxes, net of federal effect	0.70%	0.70%	0.60%
Stock-based compensation expense rate	1.50%	1.70%	1.40%
Research and development tax credits	(5.20%)	(3.00%)	(1.60%)
Tax exempt interest	(0.10%)	(0.20%)	(0.20%)
U.S. manufacturing tax incentives	(1.10%)	(0.30%)	(2.00%)
Foreign rate differential	(9.50%)	(9.10%)	(8.90%)
Audit settlements	(2.30%)
Other	2.00%	0.60%	0.10%
Effective tax rate	21.00%	25.40%	24.40%
Unrecognized Tax Benefits	$ 75,168	$ 65,161	$ 31,351	$ 32,468
Unrecognized tax benefits if recognized, would affect our effective tax rate	$ 62,100

Foreign earnings indefinitely reinvested.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to deduction for qualified production activity.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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