Fair Value Measurements (Financial Assets And Liabilities At Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Sep. 30, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents - Money Market Mutual Funds	$ 46,113		$ 32,444
Margin Deposit Assets	364		19,701
Total Assets	103,890		152,816
Total Liabilities	24,527		9,674
Total Net Assets/(Liabilities)	79,363		143,142
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents - Money Market Mutual Funds	46,113		32,444
Margin Deposit Assets	364		19,701
Total Assets	80,622		81,272
Total Liabilities	2,760		7,833
Total Net Assets/(Liabilities)	77,862		73,439
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents - Money Market Mutual Funds	0		0
Margin Deposit Assets	0		0
Total Assets	41,751		75,292
Total Liabilities	20,586		179
Total Net Assets/(Liabilities)	21,165		75,113
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents - Money Market Mutual Funds	0		0
Margin Deposit Assets	0		0
Total Assets	559		10,420
Total Liabilities	20,223		15,830
Total Net Assets/(Liabilities)	(19,664)		(5,410)
Netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents - Money Market Mutual Funds	0	[1]	0	[1]
Margin Deposit Assets	0	[1]	0	[1]
Total Assets	(19,042)	[1]	(14,168)	[1]
Total Liabilities	(19,042)	[1]	(14,168)	[1]
Total Net Assets/(Liabilities)	0	[1]	0	[1]
Commodity Futures Contracts - Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	1,588		0
Derivative Financial Instruments	0		3,292
Commodity Futures Contracts - Gas [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	4,348		4,541
Derivative Financial Instruments	2,760		7,833
Commodity Futures Contracts - Gas [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	0		0
Derivative Financial Instruments	0		0
Commodity Futures Contracts - Gas [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	0		0
Derivative Financial Instruments	0		0
Commodity Futures Contracts - Gas [Member] | Netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	(2,760)	[1]	(4,541)	[1]
Derivative Financial Instruments	(2,760)	[1]	(4,541)	[1]
Over The Counter Swaps - Oil [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	0		972
Derivative Financial Instruments	20,318		6,382
Over The Counter Swaps - Oil [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	0		0
Derivative Financial Instruments	0		0
Over The Counter Swaps - Oil [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	0		0
Derivative Financial Instruments	654		0
Over The Counter Swaps - Oil [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	559		10,420
Derivative Financial Instruments	20,223		15,830
Over The Counter Swaps - Oil [Member] | Netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	(559)	[1]	(9,448)	[1]
Derivative Financial Instruments	(559)	[1]	(9,448)	[1]
Over The Counter Swaps - Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	26,028		75,113
Derivative Financial Instruments	4,209		0
Over The Counter Swaps - Gas [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	0		0
Derivative Financial Instruments	0		0
Over The Counter Swaps - Gas [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	41,751		75,292
Derivative Financial Instruments	19,932		179
Over The Counter Swaps - Gas [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	0		0
Derivative Financial Instruments	0		0
Over The Counter Swaps - Gas [Member] | Netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments	(15,723)	[1]	(179)	[1]
Derivative Financial Instruments	(15,723)	[1]	(179)	[1]
Balanced Equity Mutual Fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	24,767		19,882
Balanced Equity Mutual Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	24,767		19,882
Balanced Equity Mutual Fund [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0		0
Balanced Equity Mutual Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0		0
Balanced Equity Mutual Fund [Member] | Netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0	[1]	0	[1]
Common Stock - Financial Services Industry [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	4,758		4,478
Common Stock - Financial Services Industry [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	4,758		4,478
Common Stock - Financial Services Industry [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0		0
Common Stock - Financial Services Industry [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0		0
Common Stock - Financial Services Industry [Member] | Netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0	[1]	0	[1]
Other Common Stock [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	272		226
Other Common Stock [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	272		226
Other Common Stock [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0		0
Other Common Stock [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	0		0
Other Common Stock [Member] | Netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Investments	$ 0	[1]	$ 0	[1]

[1] Amounts represent the impact of legally-enforceable master netting arrangements that allow the Company to net gain and loss positions held with the same counterparties.