Stock-based compensation (Details Textuals) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Oct. 31, 2011 Year	Oct. 31, 2010	Oct. 31, 2009
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Weighted Average Grant Date Fair Value	$ 16.80	$ 11.08	$ 5.31
Stock-based Compensation (Textuals) [Abstract]
Percentage of common shares available for grant from Outstanding common shares	2.50%
No of shares available for grant	1,640,000
Compensation expense recognized	$ 2,906	$ 2,231	$ 3,026
Unrecognized compensation cost from nonvested stock options	6,859
Weighted average period expected to amortized	2
Weighted-average expected volatility used	0.443%	0.436%
Weighted-average dividend yield used		1.39%
Total intrinsic value of options exercised	23,076	22,821	2,024
Cash received from exercise of stock options	9,652	13,828	2,986
Tax benefit realized from tax deductions from exercises of stock options	6,924	7,798	284
Designated period of time non vested common shares cannot be disposed of	generally six months to five years
Unrecognized compensation cost related to nonvested common shares	1,614
Weighted average period expected to amortized, non vested shares	1.7
Expense related to non vested common shares	1,278	774	507
Expense related to director deferred compensation	265	351	333
Periods of performance considered for calculating compensation expense	Over three years
Compensation expense charged	4,067	3,879	(5,014)
Cumulative amount recorded in shareholders' equity	$ 6,081	$ 3,879	$ 0
Beginning period of option exercised	1 year
Option Expiring period	10 years
Share Based Payment Award Vesting Rights	25 percent per year for executive officers and 20 percent per year for other employees
Number of common shares reserved for future issuance	139,354
Executive Officer and Selected Other Key Employees [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Weighted Average Grant Date Fair Value	$ 42.02	$ 26.10	$ 13.23
Executive Officer [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Weighted Average Grant Date Fair Value	$ 42.02	$ 29.52	$ 13.23
Other Employees [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Weighted Average Grant Date Fair Value	$ 42.02	$ 26.10	$ 13.23