Regulatory Matters (Schedule Of Regulatory Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	$ 446,194	[1]	$ 731,515	[1]
Less: Amounts Included in Other Current Assets	(26,995)	[1]	(29,726)	[1]
Total Long-Term Regulatory Assets	252,568		546,851
Total Regulatory Liabilities	337,667		265,270
Less: Amounts Included in Current and Accrued Liabilities	(32,841)		(38,253)
Total Long-Term Regulatory Liabilities	61,549		21,014
Cost Of Removal Regulatory Liability [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	157,622		139,611
Taxes Refundable To Customers [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	85,655		66,392
Post-Retirement Benefit Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	37,923		3,885
Amounts Payable To Customers [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	12,828		19,964
Off-System Sales And Capacity Release Credits [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	10,228	[2]	16,262	[2]
Other Accruals and Current Liabilities [Member]
Regulatory Assets And Liabilities [Line Items]
Less: Amounts Included in Current and Accrued Liabilities	(9,785)		(2,027)
Other Regulatory Liabilities [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Liabilities	33,411	[3]	19,156	[3]
Total Long-Term Regulatory Liabilities	23,626		17,129
Non-Current Regulatory Liabilities [Member]
Regulatory Assets And Liabilities [Line Items]
Total Long-Term Regulatory Liabilities	304,826		227,017
Pension Costs Asset [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	187,181	[1],[4]	344,228	[1],[4]
Post-Retirement Benefit Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	29,838	[1],[4]	154,415	[1],[4]
Recoverable Future Taxes [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	163,355	[1]	150,941	[1]
Environmental Site Remediation Costs [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	18,104	[1],[4]	17,843	[1],[4]
NYPSC Assessment [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	13,169	[1],[5]	17,420	[1],[5]
Asset Retirement Obligations [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	11,837	[1],[4]	26,942	[1],[4]
Unamortized Debt Expense [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	3,276	[1]	3,997	[1]
Other Regulatory Assets [Member]
Regulatory Assets And Liabilities [Line Items]
Total Regulatory Assets	19,434	[1],[6]	15,729	[1],[6]
Total Long-Term Regulatory Assets	5,608		3,423
Other Current Assets [Member]
Regulatory Assets And Liabilities [Line Items]
Less: Amounts Included in Other Current Assets	(13,826)		(12,306)
Long-Term Regulatory Assets [Member]
Regulatory Assets And Liabilities [Line Items]
Total Long-Term Regulatory Assets	$ 419,199	[1]	$ 701,789	[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, 2013 and September 30, 2012 since such amounts are expected to be passed back to ratepayers in the next 12 months.

[3] $9,785 and $2,027 are included in Other Accruals and Current Liabilities on the Consolidated Balance Sheets at September 30, 2013 and 2012, respectively, since such amounts are expected to be recovered from ratepayers in the next 12 months. $23,626 and $17,129 are included in Other Regulatory Liabilities on the Consolidated Balance Sheets at September 30, 2013 and 2012, 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, 2013 and September 30, 2012 since such amounts are expected to be recovered from ratepayers in the next 12 months.

[6] $13,826 and $12,306 are included in Other Current Assets on the Consolidated Balance Sheets at September 30, 2013 and 2012, respectively, since such amounts are expected to be recovered from ratepayers in the next 12 months. $5,608 and $3,423 are included in Other Regulatory Assets on the Consolidated Balance Sheets at September 30, 2013 and 2012, respectively.