Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013
Earnings Per Share Disclosure [Line Items]
Net income	$ 50,988	$ 24,371	$ 79,859	$ 17,428
Distributed and undistributed (earnings) to unvested restricted stock	(1,390)	(679)	(2,198)	(501)
Distributed and undistributed earnings to common shareholders-Basic	$ 49,598	$ 23,692	$ 77,661	$ 16,927
Weighted average shares outstanding-Basic	22,441	22,371	22,432	22,343
Weighted average shares outstanding-Diluted	22,441	22,371	22,432	22,343
Earnings per common share-Basic	$ 2.21	$ 1.06	$ 3.46	$ 0.76
Earnings per common share-Diluted	$ 2.21	$ 1.06	$ 3.46	$ 0.76