Short-Term Investments (Details) - USD ($) $ in Thousands		12 Months Ended
		Oct. 03, 2015	Sep. 27, 2014
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Cash and cash equivalent, Cost Basis		$ 130,607	$ 91,217
Cash and cash equivalent, Fair Value		130,607	91,217
Available-for-sale securities: Cost Basis		192,609	226,077
Available-for-sale securities: Unrealized Gains		2,301	1,026
Available-for-sale securities: Unrealized Losses		(2)	(45)
Available-for-sale securities, Fair Value		194,908	227,058
Available-for-sale Securities, Debt Maturities [Abstract]
Due in less than 1 year, Amortized Cost		148,088	178,329
Due in less than 1 year, Estimated Fair Value		149,100	179,223
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	[1]	29,252	47,748
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	[1]	29,330	47,835
Proceeds from sale of available-for-sale securities		163,800	37,300
Cash and Cash Equivalents [Member]
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale securities: Unrealized Gains		0	0
Available-for-sale securities: Unrealized Losses		0	0
Commercial Paper [Member]
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale securities: Cost Basis		9,740	23,983
Available-for-sale securities: Unrealized Gains		0	0
Available-for-sale securities: Unrealized Losses		0	0
Available-for-sale securities, Fair Value		9,740	23,983
US Treasury and Government [Member]
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale securities: Cost Basis		149,708	149,260
Available-for-sale securities: Unrealized Gains		1,040	831
Available-for-sale securities: Unrealized Losses		0	(3)
Available-for-sale securities, Fair Value		150,748	150,088
Corporate notes and obligations
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale securities: Cost Basis		17,892	52,834
Available-for-sale securities: Unrealized Gains		52	195
Available-for-sale securities: Unrealized Losses		(2)	(42)
Available-for-sale securities, Fair Value		17,942	52,987
Equity Securities [Member]
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale securities: Cost Basis		15,269
Available-for-sale securities: Unrealized Gains		1,209
Available-for-sale securities: Unrealized Losses		0
Available-for-sale securities, Fair Value		16,478
Maximum [Member]
Available-for-sale Securities, Debt Maturities [Abstract]
Realized gross gains from sale of available-for-sale securities		$ 100	$ 100

[1] Classified as short-term investments because these securities are highly liquid and can be sold at any time.