Selected Quarterly Financial Data (Details) (USD $)	3 Months Ended								12 Months Ended
	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2010	Apr. 30, 2010	Jan. 31, 2010	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2009
Selected Quarterly Financial Data Details [Abstract]
Operating Revenues	$ 192,008,000	$ 197,274,000	$ 392,567,000	$ 652,056,000	$ 194,110,000	$ 211,603,000	$ 472,846,000	$ 673,736,000	$ 1,433,905,000	$ 1,552,295,000	$ 1,638,116,000
Margin	88,739,000	81,963,000	172,931,000	230,006,000	83,075,000	77,897,000	168,678,000	222,942,000	573,639,000	552,592,000	561,574,000
Operating Income (Loss)	(1,174,000)	389,000	52,927,000	90,869,000	1,723,000	(3,471,000)	52,225,000	87,801,000	143,011,000	138,278,000	151,375,000
Net Income (Loss)	$ (9,577,000)	$ (8,703,000)	$ 47,408,000	$ 84,440,000	$ (9,102,000)	$ (9,518,000)	$ 46,825,000	$ 113,749,000	$ 113,568,000	$ 141,954,000	$ 122,824,000
Earnings (Loss) Per Share of Common Stock
Basic EPS	$ (0.13)	$ (0.12)	$ 0.66	$ 1.17	$ (0.13)	$ (0.13)	$ 0.65	$ 1.55	$ 1.58	$ 1.96	$ 1.68
Diluted EPS	$ (0.13)	$ (0.12)	$ 0.66	$ 1.16	$ (0.13)	$ (0.13)	$ 0.65	$ 1.55	$ 1.57	$ 1.96	$ 1.67