Financial Instruments & Related Fair Value (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Apr. 30, 2012 mmbtu	Apr. 30, 2011	Apr. 30, 2012	Apr. 30, 2011	Oct. 31, 2011 mmbtu
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Derivatives Held For Distribution Operations	$ 2,606,000		$ 2,606,000		$ 2,772,000
Total trading (fair value)	2,367,000		2,367,000		1,491,000
Total Fair Value Assets	4,973,000		4,973,000		4,263,000
Long Term Debt Fair Value	844,566,000		844,566,000		831,323,000
Long Term Debt Carrying Value	675,000,000		675,000,000		675,000,000
Commercial Paper Reclassed Long Term Debt	300,000,000		300,000,000
Gas Options Total Coverage	44,600,000				38,100,000
Amount Of Loss Recognized On Derivatives	2,365,000	1,903,000	5,288,000	6,125,000
Amount Of Loss Deferred Under PGA Procedures	2,365,000	1,903,000	5,288,000	6,125,000
Percentage Of Annual Gas Costs Approved For Recovery Under TIP	1.00%
Fair Value Measurement Transfers Between Levels Activity	0	0
Derivative [Line Items]
Gas Purchase Options Current Assets	2,606,000		2,606,000		2,772,000
Money markets
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Total trading (fair value)	217,000		217,000		217,000
Mutual funds
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Total trading (fair value)	2,150,000		2,150,000		1,274,000
Quoted Prices In Active Markets [Member]
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Derivatives Held For Distribution Operations	2,606,000		2,606,000		2,772,000
Total Fair Value Assets	4,973,000		4,973,000		4,263,000
Quoted Prices In Active Markets [Member] | Money markets
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Total trading (fair value)	217,000		217,000		217,000
Quoted Prices In Active Markets [Member] | Mutual funds
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Total trading (fair value)	2,150,000		2,150,000		1,274,000
Significant Other Observable Inputs [Member]
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Derivatives Held For Distribution Operations	0		0		0
Total Fair Value Assets	0		0		0
Significant Other Observable Inputs [Member] | Money markets
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Total trading (fair value)	0		0		0
Significant Other Observable Inputs [Member] | Mutual funds
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Total trading (fair value)	0		0		0
Significant Unobservable Inputs [Member]
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Derivatives Held For Distribution Operations	0		0		0
Total Fair Value Assets	0		0		0
Significant Unobservable Inputs [Member] | Money markets
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Total trading (fair value)	0		0		0
Significant Unobservable Inputs [Member] | Mutual funds
Fair Value Assets Measured On Recurring Basis Financial Statement Captions [Line Items]
Total trading (fair value)	$ 0		$ 0		$ 0