Short-Term And Long-Term Investments (Schedule Of Investments That Have Been In A Continuous Unrealized Loss Position) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Continuous Loss Position, Unrealized Loss, Less Than 12 Months	$ 508,997
Fair Value, Continuous Loss Position, Unrealized Loss, 12 Months or Greater	6,217
Fair Value, Continuous Loss Position, Unrealized Loss, Total	515,214
Gross Unrealized Losses, Continuous Loss Position, Less Than 12 Months	(874)
Gross Unrealized Losses, Continuous Loss Position, 12 Months or Greater	(265)
Gross Unrealized Losses, Continuous Loss Position, Total	(1,139)
Corporate Bonds And Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Continuous Loss Position, Unrealized Loss, Less Than 12 Months	171,144
Fair Value, Continuous Loss Position, Unrealized Loss, 12 Months or Greater	3,181
Fair Value, Continuous Loss Position, Unrealized Loss, Total	174,325
Gross Unrealized Losses, Continuous Loss Position, Less Than 12 Months	(397)
Gross Unrealized Losses, Continuous Loss Position, 12 Months or Greater	(1)
Gross Unrealized Losses, Continuous Loss Position, Total	(398)
Municipal Bonds And Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Continuous Loss Position, Unrealized Loss, Less Than 12 Months	20,080
Fair Value, Continuous Loss Position, Unrealized Loss, 12 Months or Greater	0
Fair Value, Continuous Loss Position, Unrealized Loss, Total	20,080
Gross Unrealized Losses, Continuous Loss Position, Less Than 12 Months	(15)
Gross Unrealized Losses, Continuous Loss Position, 12 Months or Greater	0
Gross Unrealized Losses, Continuous Loss Position, Total	(15)
Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Continuous Loss Position, Unrealized Loss, Less Than 12 Months	0
Fair Value, Continuous Loss Position, Unrealized Loss, 12 Months or Greater	3,036
Fair Value, Continuous Loss Position, Unrealized Loss, Total	3,036
Gross Unrealized Losses, Continuous Loss Position, Less Than 12 Months	0
Gross Unrealized Losses, Continuous Loss Position, 12 Months or Greater	(264)
Gross Unrealized Losses, Continuous Loss Position, Total	(264)
U.S. Government Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Continuous Loss Position, Unrealized Loss, Less Than 12 Months	317,773
Fair Value, Continuous Loss Position, Unrealized Loss, 12 Months or Greater	0
Fair Value, Continuous Loss Position, Unrealized Loss, Total	317,773
Gross Unrealized Losses, Continuous Loss Position, Less Than 12 Months	(462)
Gross Unrealized Losses, Continuous Loss Position, 12 Months or Greater	0
Gross Unrealized Losses, Continuous Loss Position, Total	$ (462)
Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Liquidity days for the securities provided by auction process	7 days
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Liquidity days for the securities provided by auction process	35 days