SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, PUBLIC UTILITIES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Public Utility, Property, Plant and Equipment [Line Items]
Composite rate of depreciation	2.39%	2.24%	2.34%
Property, Plant and Equipment, Gross	$ 1,706,164	$ 1,558,845
Accumulated depreciation	(410,237)	(423,126)
Property, plant and equipment, net	1,295,927	1,135,719
Distribution Facilities [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Useful Lives, Minimum, Years	38
Estimated Useful Lives, Maximum, Years	74
Transmission Facilities [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Useful Lives, Minimum, Years	35
Estimated Useful Lives, Maximum, Years	56
Storage Facilities [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Useful Lives, Minimum, Years	34
Estimated Useful Lives, Maximum, Years	47
Solar Property [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Useful Lives, Minimum, Years	20
Estimated Useful Lives, Maximum, Years	25
All other property [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Useful Lives, Minimum, Years	5
Estimated Useful Lives, Maximum, Years	35
Regulated Operation [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Distribution facilities	1,304,182	1,229,695
Transmission facilities	200,051	186,213
Storage facilities	42,364	42,105
Solar facilities		2,641
Unregulated Operation [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Solar facilities	78,322
All other property	$ 81,245	$ 98,191