Capital shares (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2009
Common shares repurchased
Number of shares	3,024	697	394
Total amount	$ 134,163	$ 22,047	$ 6,826
Average per share	$ 44.37	$ 31.63	$ 17.31