Stock Repurchase Program (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended
	May 25, 2011	Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2012		Apr. 30, 2011	Apr. 30, 2012 Accelerated Share Repurchase Agreement [Member]	Jan. 31, 2012 Accelerated Share Repurchase Agreement [Member]	Apr. 30, 2012 Accelerated Share Repurchase Agreement [Member]	Oct. 31, 2011 Accelerated Share Repurchase Agreement [Member]	Jan. 31, 2012 Accelerated Share Repurchase Agreement [Member]	Oct. 31, 2011 Accelerated Share Repurchase Agreement [Member]	Jan. 06, 2012 Accelerated Share Repurchase Agreement [Member]	Sep. 30, 2011 Accelerated Share Repurchase Agreement [Member]
Stock Repurchase Program [Line Items]
Accelerated share repurchase agreement amount													$ 40.0	$ 75.0
Stock repurchase program authorized amount	500.0			500.0
Stock repurchase program prepayment													40.0	75.0
Stock repurchase program remaining authorized repurchase amount				272.4
Initial number of shares received from accelerated share repurchase agreements								744,325				1,710,376
Number of shares to settle equity forward contract							624,291	1,105,457
Average purchase price per share		$ 32.04	$ 27.46	$ 29.64	[1]	$ 27.29		$ 26.64	$ 29.23
Initial share value								20.0				41.7
Remaining balance of value or shares to be settled								$ 20.0		$ 33.3
Additional accelerated share repurchase agreement entered date											Jan. 06, 2012

[1] Amount includes $20.0 million from the settlement of the January 2012 ASR equity forward contract and $33.3 million from the settlement of the September 2011 ASR equity forward contract.