Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2011
Earnings Per Share Disclosure [Line Items]
Net income (loss)	$ 45,270	$ 67,919	$ 24,371	$ (6,943)	$ 9,347	$ 28,721	$ 23,865	$ (7,989)	$ 130,617	$ 53,944	$ (127,077)
Distributed and undistributed (earnings) losses to unvested restricted stock									(3,704)	(1,612)	0
Distributed and undistributed earnings (losses) to common shareholders - Basic									$ 126,913	$ 52,332	$ (127,077)
Weighted average shares outstanding - Basic									22,363	22,280	22,130
Weighted average shares outstanding - Diluted									22,363	22,282	22,130
Earnings per common share - Basic									$ 5.68	$ 2.35	$ (5.74)
Earnings per common share - Diluted	$ 1.97	$ 2.95	$ 1.06	$ (0.31)	$ 0.41	$ 1.25	$ 1.05	$ (0.36)	$ 5.68	$ 2.35	$ (5.74)