REGULATORY MATTERS - Schedule of Regulatory Assets and Liabilities (Details) (USD $) | Dec. 31, 2014 | Sep. 30, 2014 |
In Millions, unless otherwise specified |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | $87.20 | $80.80 |
Regulatory Assets: Non-current | 615.8 | 614.3 |
Total Regulatory Assets | 703 | 695.1 |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 75.9 | 63.7 |
Regulatory Liabilities: Non-current | 122.9 | 125.8 |
Total Regulatory Liabilities | 198.8 | 189.5 |
RSE adjustment | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 17 | 19.8 |
Unbilled service margin | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 20.8 | 5.2 |
Pension and postretirement benefit costs | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 2.3 | 2.3 |
Refundable negative salvage | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 13.1 | 13.4 |
Regulatory Liabilities: Non-current | 25.6 | 26.8 |
Gas Supply Adjustment | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 22.1 | 22.4 |
Other | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 0.6 | 0.6 |
Unamortized investment tax credits | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 2.6 | 2.7 |
Postretirement liabilities | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 25.6 | 26.2 |
Rate recovery of asset removal cost | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 59.3 | 60.5 |
Other | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 9.8 | 9.6 |
Total Regulatory Liabilities (non-current) | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 122.9 | 125.8 |
Pension and postretirement benefit costs | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 21.4 | 21.4 |
Regulatory Assets: Non-current | 426.1 | 431.5 |
Unamortized purchased gas adjustments | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 60.6 | 54 |
Future income taxes due from customers | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 121.3 | 117 |
Rate recovery of asset removal cost | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 2.3 | 2.8 |
Accretion and depreciation of asset retirement obligations | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 18.8 | 18.4 |
Enhanced stability reserve | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 3.3 | 3.3 |
Purchased gas costs | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 4.2 | 4.3 |
Compensated absences | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 8.2 | 8.2 |
Other | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 5.2 | 5.4 |
Regulatory Assets: Non-current | 31.6 | 28.8 |
Total Regulatory Assets (non-current) | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 615.8 | 614.3 |
Laclede Gas | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 78.6 | 72 |
Regulatory Assets: Non-current | 526.9 | 523.7 |
Total Regulatory Assets | 605.5 | 595.7 |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 0.6 | 0.6 |
Regulatory Liabilities: Non-current | 70.9 | 72.1 |
Total Regulatory Liabilities | 71.5 | 72.7 |
Laclede Gas | RSE adjustment | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 0 | 0 |
Laclede Gas | Unbilled service margin | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 0 | 0 |
Laclede Gas | Pension and postretirement benefit costs | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 0 | 0 |
Laclede Gas | Refundable negative salvage | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 0 | 0 |
Regulatory Liabilities: Non-current | 0 | 0 |
Laclede Gas | Gas Supply Adjustment | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 0 | 0 |
Laclede Gas | Other | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 0.6 | 0.6 |
Laclede Gas | Unamortized investment tax credits | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 2.6 | 2.7 |
Laclede Gas | Postretirement liabilities | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 0 | 0 |
Laclede Gas | Rate recovery of asset removal cost | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 59.3 | 60.5 |
Laclede Gas | Other | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 9 | 8.9 |
Laclede Gas | Total Regulatory Liabilities (non-current) | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 70.9 | 72.1 |
Laclede Gas | Pension and postretirement benefit costs | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 15 | 15 |
Regulatory Assets: Non-current | 361.6 | 365.4 |
Laclede Gas | Unamortized purchased gas adjustments | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 60.6 | 54 |
Laclede Gas | Future income taxes due from customers | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 121.3 | 117 |
Laclede Gas | Rate recovery of asset removal cost | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 0 | 0 |
Laclede Gas | Accretion and depreciation of asset retirement obligations | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 0 | 0 |
Laclede Gas | Enhanced stability reserve | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 0 | 0 |
Laclede Gas | Purchased gas costs | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 4.2 | 4.3 |
Laclede Gas | Compensated absences | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 8.2 | 8.2 |
Laclede Gas | Other | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 3 | 3 |
Regulatory Assets: Non-current | 31.6 | 28.8 |
Laclede Gas | Total Regulatory Assets (non-current) | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 526.9 | 523.7 |
Alagasco | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 8.6 | 8.8 |
Regulatory Assets: Non-current | 88.9 | 90.6 |
Total Regulatory Assets | 97.5 | 99.4 |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 75.3 | 63.1 |
Regulatory Liabilities: Non-current | 51.9 | 53.7 |
Total Regulatory Liabilities | 127.2 | 116.8 |
Alagasco | RSE adjustment | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 17 | 19.8 |
Alagasco | Unbilled service margin | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 20.8 | 5.2 |
Alagasco | Pension and postretirement benefit costs | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 2.3 | 2.3 |
Alagasco | Refundable negative salvage | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 13.1 | 13.4 |
Regulatory Liabilities: Non-current | 25.6 | 26.8 |
Alagasco | Gas Supply Adjustment | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 22.1 | 22.4 |
Alagasco | Other | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Current | 0 | 0 |
Alagasco | Unamortized investment tax credits | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 0 | 0 |
Alagasco | Postretirement liabilities | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 25.6 | 26.2 |
Alagasco | Rate recovery of asset removal cost | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 0 | 0 |
Alagasco | Other | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 0.7 | 0.7 |
Alagasco | Total Regulatory Liabilities (non-current) | | |
Regulatory Liabilities [Line Items] | | |
Regulatory Liabilities: Non-current | 51.9 | 53.7 |
Alagasco | Pension and postretirement benefit costs | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 6.4 | 6.4 |
Regulatory Assets: Non-current | 64.5 | 66.1 |
Alagasco | Unamortized purchased gas adjustments | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 0 | 0 |
Alagasco | Future income taxes due from customers | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 0 | 0 |
Alagasco | Rate recovery of asset removal cost | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 2.3 | 2.8 |
Alagasco | Accretion and depreciation of asset retirement obligations | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 18.8 | 18.4 |
Alagasco | Enhanced stability reserve | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 3.3 | 3.3 |
Alagasco | Purchased gas costs | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 0 | 0 |
Alagasco | Compensated absences | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | 0 | 0 |
Alagasco | Other | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Current | 2.2 | 2.4 |
Regulatory Assets: Non-current | 0 | 0 |
Alagasco | Total Regulatory Assets (non-current) | | |
Regulatory Assets [Line Items] | | |
Regulatory Assets: Non-current | $88.90 | $90.60 |