COMMITMENTS AND CONTINGENT LIABILITIES, LEGAL PROCEEDINGS (Details) (USD $)	6 Months Ended
	Mar. 31, 2012	Sep. 30, 2011
Site Contingency [Line Items]
Site Contingency, Recovery from Third Party of Environmental Remediation Cost	$ 20,000,000
Regulatory assets	410,901,000	434,185,000
Maximum [Member]
Site Contingency [Line Items]
Litigation Settlement, Gross	278,500,000
Minimum [Member]
Site Contingency [Line Items]
Litigation Settlement, Gross	161,500,000
Enviromental remediation costs expended, net of recoveries [Member]
Site Contingency [Line Items]
Regulatory assets	61,259,000	75,646,000
Enviromental remediation costs liability for future expenditures [Member]
Site Contingency [Line Items]
Regulatory assets	$ 182,900,000	$ 182,900,000