Marketable Securities (Details) - USD ($) $ in Thousands	Apr. 01, 2017	Sep. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 48,384	$ 49,738
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Loss	(193)	(122)
Available-for-sale Securities	48,191	49,616
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Amortized Cost Basis	23,492	18,585
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	23,449	18,549
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Amortized Cost Basis	24,892	31,153
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	24,742	31,067
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	682	681
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Loss	0	0
Available-for-sale Securities	682	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	7,492	11,945
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Loss	(2)	(20)
Available-for-sale Securities	7,490	11,925
Corporate notes/bonds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	37,801	34,701
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Loss	(184)	(100)
Available-for-sale Securities	37,617	34,601
U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	2,409	2,411
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Loss	(7)	(2)
Available-for-sale Securities	$ 2,402	$ 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=51813488&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=49167202&loc=d3e26610-111562

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

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