Calculation of Earnings (Loss) Per Share (Detail) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2011	Jul. 31, 2010
Earnings Per Share Disclosure [Line Items]
Net income (loss)	$ (55,683)	$ 36,116	$ (105,515)	$ 87,020
Earnings (loss) per common share - Basic	$ (2.51)	$ 1.55	$ (4.77)	$ 3.96
Earnings (loss) per common share - Diluted	$ (2.51)	$ 1.55	$ (4.77)	$ 3.96
Two-class method
Earnings Per Share Disclosure [Line Items]
Net income (loss)	(55,683)	36,116	(105,515)	87,020
Distributed and undistributed (earnings) losses to unvested restricted stock	0	(908)	0	(2,343)
Distributed and undistributed earnings (losses) to common shareholders - Basic	(55,683)	35,208	(105,515)	84,677
Weighted average shares outstanding - Basic	22,142	22,730	22,124	21,370
Weighted average shares outstanding - Diluted	22,142	22,734	22,124	21,378
Earnings (loss) per common share - Basic	$ (2.51)	$ 1.55	$ (4.77)	$ 3.96
Earnings (loss) per common share - Diluted	$ (2.51)	$ 1.55	$ (4.77)	$ 3.96
Treasury stock method
Earnings Per Share Disclosure [Line Items]
Net income (loss)	(55,683)	36,116	(105,515)	87,020
Distributed and undistributed (earnings) losses to unvested restricted stock	0	0	0	0
Distributed and undistributed earnings (losses) to common shareholders - Basic	$ (55,683)	$ 36,116	$ (105,515)	$ 87,020
Weighted average shares outstanding - Basic	22,142	22,730	22,124	21,370
Weighted average shares outstanding - Diluted	22,142	23,081	22,124	21,725
Earnings (loss) per common share - Basic	$ (2.51)	$ 1.59	$ (4.77)	$ 4.07
Earnings (loss) per common share - Diluted	$ (2.51)	$ 1.56	$ (4.77)	$ 4.01