Marketable Securities (Details) - USD ($) $ in Thousands	Jul. 01, 2017	Sep. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 50,361	$ 49,738
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Loss	(172)	(122)
Available-for-sale Securities	50,189	49,616
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Amortized Cost Basis	19,129	18,585
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	19,095	18,549
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Amortized Cost Basis	31,232	31,153
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	31,094	31,067
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	441	681
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Loss	0	0
Available-for-sale Securities	441	681
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		11,945
Available-for-sale Securities, Gross Unrealized Gain		0
Available-for-sale Securities, Gross Unrealized Loss		(20)
Available-for-sale Securities		11,925
Corporate notes/bonds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	47,519	34,701
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Loss	(165)	(100)
Available-for-sale Securities	47,354	34,601
U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	2,401	2,411
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Loss	(7)	(2)
Available-for-sale Securities	$ 2,394	$ 2,409

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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