Marketable Securities (Amortized Cost and Fair Value of Marketable Securities) (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Sep. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 57,381	$ 57,317
Gross unrealized gains	419	146
Gross unrealized losses	(12)	(28)
Fair value	57,788	57,435
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized cost	1,492	999
Gross unrealized gains	8	0
Gross unrealized losses	0	0
Fair value	1,500	999
Corporate notes/bonds
Debt Securities, Available-for-sale [Line Items]
Amortized cost	55,889	56,318
Gross unrealized gains	411	146
Gross unrealized losses	(12)	(28)
Fair value	$ 56,288	$ 56,436

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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