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	9 Months Ended
	Jun. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Continuous Loss Position, Unrealized Loss, Less Than 12 Months	$ 645,043
Gross Unrealized Losses, Continuous Loss Position, Less Than 12 Months	(2,286)
Fair Value, Continuous Loss Position, Unrealized Loss, 12 Months or Greater	15,229
Gross Unrealized Losses, Continuous Loss Position, 12 Months or Greater	(354)
Fair Value, Continuous Loss Position, Unrealized Loss, Total	660,272
Gross Unrealized Losses, Continuous Loss Position, Total	(2,640)
Corporate Bonds and Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Continuous Loss Position, Unrealized Loss, Less Than 12 Months	196,715
Gross Unrealized Losses, Continuous Loss Position, Less Than 12 Months	(952)
Fair Value, Continuous Loss Position, Unrealized Loss, 12 Months or Greater	7,851
Gross Unrealized Losses, Continuous Loss Position, 12 Months or Greater	(1)
Fair Value, Continuous Loss Position, Unrealized Loss, Total	204,566
Gross Unrealized Losses, Continuous Loss Position, Total	(953)
Municipal Bonds and Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Continuous Loss Position, Unrealized Loss, Less Than 12 Months	14,787
Gross Unrealized Losses, Continuous Loss Position, Less Than 12 Months	(37)
Fair Value, Continuous Loss Position, Unrealized Loss, 12 Months or Greater	0
Gross Unrealized Losses, Continuous Loss Position, 12 Months or Greater	0
Fair Value, Continuous Loss Position, Unrealized Loss, Total	14,787
Gross Unrealized Losses, Continuous Loss Position, Total	(37)
Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Continuous Loss Position, Unrealized Loss, Less Than 12 Months	0
Gross Unrealized Losses, Continuous Loss Position, Less Than 12 Months	0
Fair Value, Continuous Loss Position, Unrealized Loss, 12 Months or Greater	4,048
Gross Unrealized Losses, Continuous Loss Position, 12 Months or Greater	(352)
Fair Value, Continuous Loss Position, Unrealized Loss, Total	4,048
Gross Unrealized Losses, Continuous Loss Position, Total	(352)
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	433,541
Gross Unrealized Losses, Continuous Loss Position, Less Than 12 Months	(1,297)
Fair Value, Continuous Loss Position, Unrealized Loss, 12 Months or Greater	3,330
Gross Unrealized Losses, Continuous Loss Position, 12 Months or Greater	(1)
Fair Value, Continuous Loss Position, Unrealized Loss, Total	436,871
Gross Unrealized Losses, Continuous Loss Position, Total	$ (1,298)
Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Liquidity days for the security provided by auction process	7 days
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Liquidity days for the security provided by auction process	35 days