Accumulated Other Comprehensive Loss and Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2010
Accumulated Other Comprehensive Loss and Total Comprehensive Income (Loss)
Net income (loss)	$ 411,417	$ 61,643	$ 16,872	$ (2,786)	$ 15,043	$ 42,108	$ (20,773)	$ 3,417	$ 487,146	$ 39,795	$ (3,374)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent									(1,839)	(1,934)	1,986
Change in fair value of available-for-sale securities									476	(192)	74
Unrealized loss on derivative held by equity investee									(554)
Comprehensive (loss) income									485,229	37,669	(1,314)
Other Comprehensive Income (Loss), Tax									$ 1,263