Stockholders' Equity (Details) (USD $)	0 Months Ended					3 Months Ended				12 Months Ended			0 Months Ended
	Aug. 06, 2012	Feb. 07, 2012	Dec. 15, 2011	Aug. 05, 2011	Feb. 07, 2011	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2010	Dec. 05, 2012 Subsequent Event [Member]
Class of Stock [Line Items]
Share repurchase program, maximum amount authorized			$ 150,000,000										$ 300,000,000
Number of shares purchased						0	321,000	0	663,000	984,027	0
Cost of common stock repurchased							25,000,000		46,100,000	71,150,000
Share repurchase program, remaining authorized amount										78,900,000			228,900,000
Average purchase price per share							$ 77.89		$ 69.60
Dividends on common stock	1,400,000	1,400,000		1,400,000	1,400,000					2,857,000	2,816,000	2,732,000
Cash dividend, per share	$ 0.03	$ 0.03		$ 0.03	$ 0.03					$ 0.03
Date of record	Jul. 24, 2012	Jan. 25, 2012		Jul. 25, 2011	Jan. 19, 2011
Common stock purchase right versus preferred share purchase right										0.5
Percentage of acquisition of beneficial ownership										20.00%
Purchase price of the Right, subject to adjustment										$ 450
Percentage of assets or earning power sold										50.00%
Board of Directors may redeem the rights at, price per right						$ 0.01				$ 0.01