REGULATION, REGULATORY FILINGS (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Jun. 30, 2011
Schedule of Regulatory [Line Items]
Weighted Cost of Capital	7.76%
BGSS [Member]
Schedule of Regulatory [Line Items]
Rate Increase (Decrease) Proposed to the Public Utility Regulatory Authority	(9.10%)
CIP [Member]
Schedule of Regulatory [Line Items]
Annual Recovery Amount Approved by the Public Utility Regulatory Authority	$ 12.1
AIP I and AIP II [Member]
Schedule of Regulatory [Line Items]
Annual Recovery Amount Proposed to the Public Utility Regulatory Authority	4.7
AIP II [Member]
Schedule of Regulatory [Line Items]
Originally Filed Petition for Capital Investments to the Public Utility Regulatory Authority	52.2
Amended Filed Petition for Capital Investments to the Public Utility Regulatory Authority	60.2
Weighted Cost of Capital	7.12%
Return on Equity	10.30%
USF [Member]
Schedule of Regulatory [Line Items]
Rate Increase (Decrease) Proposed to the Public Utility Regulatory Authority	(0.10%)
Compressed Natural Gas Vehicle Refueling Stations [Member]
Schedule of Regulatory [Line Items]
Originally Filed Petition for Capital Investments to the Public Utility Regulatory Authority	$ 15.0