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Regulatory matters and revenues subject to refund (Details) (USD $) | 6 Months Ended | 9 Months Ended | 6 Months Ended | 12 Months Ended | 6 Months Ended
--- | --- | --- | --- | --- | ---
Jun. 30, 2013 MTPSC [Member] | Sep. 30, 2012 MTPSC [Member] | Jun. 30, 2013 SDPUC [Member] | Dec. 31, 2012 SDPUC [Member] | Jun. 30, 2013 NDPSC [Member]
Regulatory matters and revenues subject to refund [Line Items] |  |  |  |  |
Total gas rate increase requested |  | $ 3,500,000 |  | $ 1,500,000 |
Percent above current rates requested |  | 5.90% |  | 3.30% |
Amount of requested interim increase in annual gas rates |  | 1,700,000 | 1,500,000 |  |
Requested percentage of interim gas rate increase |  | 2.90% |  |  |
Interim rate increase (decrease), amount | 850,000 |  |  |  |
Estimated project cost |  |  |  |  | $ 26,100,000

X
- Definition The amount of requested interim increase in annual gas rates. + References No definition available. + Details
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- Definition Estimated project cost. + References No definition available. + Details
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- Details
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- Definition The percentage of interim gas rate increase requested. + References No definition available. + Details
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- Definition Amount of public utility's interim rate increase (decrease) allowed while waiting final decision of regulatory agency. + References No definition available. + Details
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- Definition Amount of public utility's requested rate increase (decrease) with regulatory agency. + References No definition available. + Details
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- Definition Percentage of public utility's requested rate increase (decrease) with regulatory agency. + References No definition available. + Details
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