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COMMITMENTS AND CONTINGENCIES - Contingencies (Details) |  | 12 Months Ended | 54 Months Ended |
--- | --- | --- | --- | ---
Dec. 17, 2013 fatality | Sep. 30, 2017 plaintiff site lawsuit | Sep. 30, 2016 lawsuit | Sep. 30, 2015 site
Site Contingency [Line Items] |  |  |  |
Number of incident fatalities | fatality | 1 |  |  |
Spire Missouri |  |  |  |
Site Contingency [Line Items] |  |  |  |
Number of former manufactured gas plant (MGP) sites in Shrewsbury, Missouri |  | 1 |  |
Number of former manufactured gas plant (MGP) sites in the City of St. Louis |  | 2 |  |
Spire Missouri | Previous Ownership |  |  |  |
Site Contingency [Line Items] |  |  |  |
Number of former manufactured gas plant (MGP) |  |  |  | 19
Missouri Gas Energy (MGE) | Previous Ownership |  |  |  |
Site Contingency [Line Items] |  |  |  |
Number of former manufactured gas plant (MGP) |  | 7 |  |
Spire Alabama |  |  |  |
Site Contingency [Line Items] |  |  |  |
Number of former manufactured gas plant (MGP) |  | 9 |  |
Number of former manufactured gas distribution |  | 5 |  |
Spire Alabama | Current Ownership |  |  |  |
Site Contingency [Line Items] |  |  |  |
Number of former manufactured gas plant (MGP) |  | 4 |  |
Number of former manufactured gas distribution |  | 1 |  |
Mobile Gas |  |  |  |
Site Contingency [Line Items] |  |  |  |
Number of lawsuits | lawsuit |  |  | 14 |
Number of lawsuits settled | lawsuit |  |  | 11 |
Number of lawsuits pending | lawsuit |  | 3 |  |
Mobile Gas | Pending Litigation |  |  |  |
Site Contingency [Line Items] |  |  |  |
Number of plaintiffs | plaintiff |  | 270 |  |
Mobile Gas | Previous Ownership |  |  |  |
Site Contingency [Line Items] |  |  |  |
Number of former manufactured gas plant (MGP) |  |  |  | 1

X
- Definition The number of manufactured gas plant (MGP) sites in Missouri posing potential environmental liability at St Louis. + References No definition available. + Details
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- Definition The total number of new claims filed pertaining to a loss contingency during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349 + Details
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