Convertible Notes Payable (Details) (USD $)	12 Months Ended				3 Months Ended		12 Months Ended		3 Months Ended	12 Months Ended			3 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended
	Oct. 31, 2011 days debtinstrument	Oct. 31, 2010	Oct. 31, 2009	Oct. 31, 2011 Embedded redemption feature [Member]	Oct. 31, 2010 0.25% Convertible Senior Notes due May 1, 2013 [Member]	Apr. 30, 2006 0.25% Convertible Senior Notes due May 1, 2013 [Member]	Oct. 31, 2011 0.25% Convertible Senior Notes due May 1, 2013 [Member]	Apr. 10, 2006 0.25% Convertible Senior Notes due May 1, 2013 [Member]	Apr. 30, 2010 4.0% Convertible Senior Notes due March 15, 2015 [Member]	Oct. 31, 2011 4.0% Convertible Senior Notes due March 15, 2015 [Member]		Mar. 15, 2010 4.0% Convertible Senior Notes due March 15, 2015 [Member]	Jul. 31, 2007 0.875% Convertible Senior Notes due June 15, 2017 [Member]	Oct. 31, 2011 0.875% Convertible Senior Notes due June 15, 2017 [Member]	Jun. 11, 2007 0.875% Convertible Senior Notes due June 15, 2017 [Member]	Oct. 31, 2010 3.75% Convertible Senior Notes due October 15, 2018 [Member]	Oct. 31, 2011 3.75% Convertible Senior Notes due October 15, 2018 [Member]	Oct. 18, 2010 3.75% Convertible Senior Notes due October 15, 2018 [Member]
Convertible Notes Payable (Textuals) [Abstract]
Number of issuances of convertible notes payable outstanding	4
Minimum percentage of aggregate principal amount required to be held by trustee or holders to declare notes immediately payable	25.00%
Interest on convertible notes							0.25%	0.25%		4.00%		4.00%		0.875%	0.875%		3.75%	3.75%
Aggregate principal amount								$ 300,000,000				$ 375,000,000			$ 500,000,000			$ 350,000,000
Amount repurchased					81,800,000
Gain on extinguishment of debt	0	4,948,000	0		4,900,000
Number of shares converted for each $1000 principal amount (in shares)							25.3001			49.0557				26.2154			49.5872
Principal amount used for conversion of notes	1,000
Initial conversion price per share equivalent (per share)							$ 39.5255			$ 20.38				$ 38.15			$ 20.17
Minimum number of trading days in 30 consecutive trading day period prior to redemption notice date where closing price exceeds conversion price by a minimum percentage	20
Number of consecutive trading day period prior to redemption notice date where closing price exceeds conversion price by a minimum percentage	30
Redemption option, closing price to conversion price, minimum percentage							130.00%			150.00%
Net proceeds from convertible senior notes offering used to purchase call spread option on its common stock						28,500,000							42,500,000
Discount rate used for make whole premium payment calculation										2.75%
Fair value of embedded redemption feature included in long-term assets	7,020,000	4,220,000		7,000,000
Change in fair value of embedded redemption feature included in interest and other income (loss)	2,800,000	2,510,000	0
Net proceeds from issuance of senior convertible notes	0	725,000,000	0						364,300,000							340,400,000
Net proceeds from convertible senior notes offering used to replace contractual obligation to issue convertible notes as part of acqusition									243,800,000
Net proceeds from convertible senior notes offering used to repurchase 0.25% convertible senior notes due 2013																76,100,000
Carrying value and estimated current fair value of outstanding convertible notes
Carrying Value	1,442,364,000	1,442,705,000					216,210,000			376,154,000	[1]			500,000,000			350,000,000
Fair Value	$ 1,327,774,000						$ 215,399,000			$ 388,125,000	[1]			$ 376,875,000			$ 347,375,000

[1] Includes unamortized bond premium related to embedded redemption feature