COMMITMENTS AND CONTINGENT LIABILITIES - LEGAL PROCEEDINGS (Details) (USD $)	3 Months Ended
	Dec. 31, 2014	Sep. 30, 2014
Site Contingency [Line Items]
Regulatory assets	$ 369,176,000	$ 377,575,000
Minimum [Member]
Site Contingency [Line Items]
Litigation settlement, gross	151,300,000
Maximum [Member]
Site Contingency [Line Items]
Litigation settlement, gross	249,800,000
Environmental Remediation Costs Expended, Net of Recoveries [Member]
Site Contingency [Line Items]
Regulatory assets	26,226,000	30,916,000
Environmental Remediation Costs Liability for Future Expenditures [Member]
Site Contingency [Line Items]
Regulatory assets	177,000,000	177,000,000
SBC [Member] | July 2013 SBC Filing [Member]
Site Contingency [Line Items]
Annual recovery amount approved by the Board of Public Utilities	18,700,000
SBC [Member] | September 2014 SBC Filing [Member]
Site Contingency [Line Items]
Requested rate, amount	$ 8,500,000