Stock Compensation Plans - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		1 Months Ended	6 Months Ended	0 Months Ended					3 Months Ended		6 Months Ended			3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014 Restricted Stock	Apr. 30, 2013 Restricted Stock	Apr. 30, 2014 Restricted Stock	Apr. 30, 2013 Restricted Stock	Nov. 30, 2013 Restricted Stock Officers and Key Management Employees	Apr. 30, 2014 Restricted Stock Officers and Key Management Employees	Feb. 13, 2014 Restricted Stock Outside Directors	Feb. 13, 2014 Restricted Stock Outside Directors Scenario 1	Feb. 13, 2014 Restricted Stock Outside Directors Scenario 2	Feb. 13, 2014 Restricted Stock Outside Directors Scenario 3	Nov. 02, 2013 Performance Based Awards	Apr. 30, 2014 Employee Stock Purchase Plan	Apr. 30, 2013 Employee Stock Purchase Plan	Apr. 30, 2014 Employee Stock Purchase Plan	Apr. 30, 2013 Employee Stock Purchase Plan	Apr. 30, 2014 Employee Stock Purchase Plan Restricted Stock	Apr. 30, 2014 Performance Share Plan 2013 Performance Based Awards	Apr. 30, 2014 Performance Share Plan 2013 Performance Based Awards	Apr. 30, 2014 Performance Share Plan 2012 Performance Based Awards	Apr. 30, 2014 Performance Share Plan 2012 Performance Based Awards	Apr. 30, 2014 Performance Share Plan 2014 Performance Based Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	$ 5,586,000	$ 1,193,000	$ 7,117,000	$ 2,359,000
Shares received by participants																				8,071
Average price per share purchased by participants																				$ 74.03
Matching shares issued																				1,965
Compensation cost					1,152,000	1,144,000	2,229,000	2,260,000								48,000	49,000	96,000	100,000		4,050,000	4,050,000	336,000	741,000	0
Target number of common stock to be granted															75,925
Aggregate number of shares outstanding					568,900		568,900														174,597	174,597	103,184	103,184
Shares of restricted stock granted									75,925		23,000
Grant date fair value of restricted shares									$ 65.63		$ 72.66
Vesting date of the restricted stock granted										Nov. 01, 2017
Vesting period												1 year	2 years	3 years
Unrecognized share-based compensation costs					$ 10,000,000		$ 10,000,000
Unrecognized share-based compensation costs recognized, weighted average period							2 years