Income taxes (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Jul. 31, 2011	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2009
Unrecognized tax benefits
Balance at beginning of year		$ 4,078	$ 3,969	$ 7,685
Additions based on tax positions related to the current year		387	388	515
Additions for tax positions of prior years		138	359
Reductions for tax positions of prior years			(638)	(3,267)
Settlements	(2,027)	(2,027)		(964)
Lapse of statute of limitations		0	0	0
Balance at end of year		$ 2,576	$ 4,078	$ 3,969