Regulatory Matters (Schedule Of Regulatory Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	$ 413,387	[1]	$ 446,194	[1]
Less: Amounts Included in Other Current Assets	(22,719)	[1]	(26,995)	[1]
Total Long-Term Regulatory Assets	224,436		252,568
Total Regulatory Liabilities	397,904		337,667
Less: Amounts Included in Current and Accrued Liabilities	(51,817)		(32,841)
Total Long-Term Regulatory Liabilities	81,152		61,549
Cost Of Removal Regulatory Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	173,199		157,622
Taxes Refundable To Customers [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	91,736		85,655
Post-Retirement Benefit Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	53,650		37,923
Amounts Payable To Customers [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	33,745		12,828
Off-System Sales And Capacity Release Credits [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	12,805	[2]	10,228	[2]
Other Accruals and Current Liabilities [Member]
Regulatory Assets And Liabilities [Line Items]
Less: Amounts Included in Current and Accrued Liabilities	(5,267)		(9,785)
Other Regulatory Liabilities [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	32,769	[3]	33,411	[3]
Total Long-Term Regulatory Liabilities	27,502		23,626
Non-Current Regulatory Liabilities [Member]
Regulatory Assets And Liabilities [Line Items]
Total Long-Term Regulatory Liabilities	346,087		304,826
Pension Costs Asset [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	164,804	[1],[4]	187,181	[1],[4]
Post-Retirement Benefit Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	17,128	[1],[4]	29,838	[1],[4]
Recoverable Future Taxes [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	163,485	[1]	163,355	[1]
Environmental Site Remediation Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	25,645	[1],[4]	18,104	[1],[4]
NYPSC Assessment [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	12,730	[1],[5]	13,169	[1],[5]
Asset Retirement Obligations [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	12,006	[1],[4]	11,837	[1],[4]
Unamortized Debt Expense [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	2,747	[1]	3,276	[1]
Other Regulatory Assets [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	14,842	[1],[6]	19,434	[1],[6]
Total Long-Term Regulatory Assets	4,853		5,608
Other Current Assets [Member]
Regulatory Assets And Liabilities [Line Items]
Less: Amounts Included in Other Current Assets	(9,989)		(13,826)
Long-Term Regulatory Assets [Member]
Regulatory Assets And Liabilities [Line Items]
Total Long-Term Regulatory Assets	$ 390,668	[1]	$ 419,199	[1]

[1] The Company recovers the cost of its regulatory assets but generally does not earn a return on them. There are a few exceptions to this rule. For example, the Company does earn a return on Unrecovered Purchased Gas Costs and, in the New York jurisdiction of its Utility segment, earns a return, within certain parameters, on the excess of cumulative funding to the pension plan over the cumulative amount collected in rates.

[2] Amounts are included in Other Accruals and Current Liabilities on the Consolidated Balance Sheets at September 30, 2014 and September 30, 2013 since such amounts are expected to be passed back to ratepayers in the next 12 months.

[3] $5,267 and $9,785 are included in Other Accruals and Current Liabilities on the Consolidated Balance Sheets at September 30, 2014 and 2013, respectively, since such amounts are expected to be recovered from ratepayers in the next 12 months. $27,502 and $23,626 are included in Other Regulatory Liabilities on the Consolidated Balance Sheets at September 30, 2014 and 2013, respectively.

[4] Included in Other Regulatory Assets on the Consolidated Balance Sheets.

[5] Amounts are included in Other Current Assets on the Consolidated Balance Sheets at September 30, 2014 and September 30, 2013 since such amounts are expected to be recovered from ratepayers in the next 12 months.

[6] $9,989 and $13,826 are included in Other Current Assets on the Consolidated Balance Sheets at September 30, 2014 and 2013, respectively, since such amounts are expected to be recovered from ratepayers in the next 12 months. $4,853 and $5,608 are included in Other Regulatory Assets on the Consolidated Balance Sheets at September 30, 2014 and 2013, respectively.