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REGULATION - REGULATORY FILINGS (Details) (USD $) | 6 Months Ended |  | 3 Months Ended |  |
--- | --- | --- | --- | --- | ---
Mar. 31, 2013 | Sep. 30, 2012 | Mar. 31, 2013 SAFE-Safety Acceleration and Facility Enhancement Program [Member] | Mar. 31, 2013 AIP I and AIP II [Member] | Mar. 31, 2013 Deferred Superstorm Storm Costs [Member] | Sep. 30, 2012 Deferred Superstorm Storm Costs [Member]
Schedule of Regulatory [Line Items] |  |  |  |  |  |
Increase (decrease) in regulatory assets and liabilities | $ 9,800,000 |  |  |  |  |
Capital investments approved by the board of public utilities |  |  | 130,000,000 |  |  |
Weighted cost of capital |  |  | 6.90% |  |  |
Public utility annual rate for allowance for funds used during construction |  |  | 6.90% |  |  |
Regulatory assets | 442,208,000 | 441,263,000 |  |  | 14,666,000 | 0
Annual recovery amount increase (decrease) proposed to the board of public utilities |  |  |  | $ 6,900,000 |  |

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- Definition Capital Investments Approved By The Board Of Public Utilities + References No definition available. + Details
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- Definition Public Utility Annual Rate for Allowance for Funds Used During Construction + References No definition available. + Details
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- Definition The increase (decrease) during the reporting period in the value of assets that are created when regulatory agencies permits public utilities to defer costs (revenues) to the balance sheet. This element is a the increase (decrease) of regulatory assets and liabilities combined. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585 + Details
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- Definition Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 71 -Paragraph 9, 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
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