Marketable Securities (Amortized Cost and Fair Value of Marketable Securities) (Details) - USD ($) $ in Thousands	Jun. 29, 2019	Sep. 30, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized cost	$ 54,561	$ 56,364
Gross unrealized gains	124	0
Gross unrealized losses	(59)	(413)
Fair value	54,626	55,951
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized cost		220
Gross unrealized gains		0
Gross unrealized losses		(1)
Fair value		219
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized cost	4,474
Gross unrealized gains	1
Gross unrealized losses	0
Fair value	4,475
Corporate notes/bonds
Debt Securities, Available-for-sale [Line Items]
Amortized cost	50,087	55,140
Gross unrealized gains	123	0
Gross unrealized losses	(59)	(403)
Fair value	$ 50,151	54,737
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost		1,004
Gross unrealized gains		0
Gross unrealized losses		(9)
Fair value		$ 995

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

No definition available.

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

No definition available.

+ Details

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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