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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - CAPITALIZED AND DEFERRED INTEREST (Details) - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015
AFUDC: |  |  |
SBC interest rate | 2.55% | 2.05% | 2.54%
Deferred interest | $ 78 | $ 54 | $ 61
Seven-Year Treasury Rate |  |  |
AFUDC: |  |  |
Debt instrument, term | 7 years |  |
Basis spread on variable rate | 60.00% |  |
Natural Gas Distribution |  |  |
AFUDC: |  |  |
Debt | $ 1,311 | 5,009 | 2,472
Equity | 3,867 | 4,375 | 3,825
Total | $ 5,178 | $ 9,384 | $ 6,297
Weighted average interest rate | 6.90% | 5.06% | 4.63%

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- Definition Total increase in earnings in the period representing the cost of equity (based on assumed rate of return) and/or borrowed funds (based on interest rate) used to finance construction of regulated assets, which is expected to be recovered through rate adjustments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44278-110382 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6500269&loc=d3e45485-110386 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
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