Short-Term Investments (Details) (USD $)	3 Months Ended					3 Months Ended
	Dec. 31, 2011	Jan. 01, 2011	Oct. 01, 2011	Dec. 31, 2011 Foreign Operations [Member]	Jan. 31, 2012 Foreign Operations [Member] US Treasury Securities [Member]	Dec. 31, 2011 Maximum [Member]	Jan. 01, 2011 Maximum [Member]	Dec. 31, 2011 Certificates of deposit	Oct. 01, 2011 Certificates of deposit	Dec. 31, 2011 US Treasury and agency obligations	Oct. 01, 2011 US Treasury and agency obligations	Dec. 31, 2011 Corporate notes and obligations	Oct. 01, 2011 Corporate notes and obligations
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Cash and cash equivalent, Cost Basis	$ 167,655,000		$ 166,931,000
Cash and cash equivalent, Unrealized Gains	7,000		131,000
Cash and cash equivalent, Unrealized Losses	0		(1,000)
Cash and cash equivalent, Fair Value	167,662,000		167,061,000
Available-for-sale securities: Cost Basis	35,149,000		52,883,000					2,000,000	6,500,000	2,667,000	1,101,000	30,482,000	45,282,000
Available-for-sale securities: Unrealized Gains	278,000		286,000					2,000	10,000	61,000	1,000	215,000	275,000
Available-for-sale securities: Unrealized Losses	(6,000)		(27,000)					0	0	(5,000)	(1,000)	(1,000)	(26,000)
Available-for-sale securities: Fair Value	35,421,000		53,142,000					2,002,000	6,510,000	2,723,000	1,101,000	30,696,000	45,531,000
Available-for-sale Securities, Debt Maturities [Abstract]
Due in less than 1 year, Amortized Cost	33,149,000		46,383,000
Due in less than 1 year, Estimated Fair Value	33,419,000		46,632,000
Total investments in available-for-sale debt securities, Amortized Cost	33,149,000		46,383,000
Total investments in available-for-sale debt securities, Estimated Fair Value	33,419,000		46,632,000							2,700,000		15,400,000
Proceeds from sale of available-for-sale securities	27,500,000	18,400,000
Realized gross gains from sale of available-for-sale securities						100,000	100,000
Gross unrealized losses on investments with unrealized losses that are deemed to be availble-for-sale securities	13,000
Cash, Cash Equivalents, and Short-term Investments				$ 142,500,000	$ 89,800,000