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Commitments and Contingencies - Additional Information - Contingencies (Details) - site | Sep. 30, 2019 | Sep. 30, 2013
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Spire Missouri East |  |
Site Contingency [Line Items] |  |
Number of former manufactured gas plant (MGP) sites in Missouri | 3 |
Number of sites enrolled in Brownfields/Voluntary clean up program | 2 |
Spire Missouri East | Previous Ownership |  |
Site Contingency [Line Items] |  |
Number of former manufactured gas plant (MGP) |  | 19
Spire Missouri West | 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 |

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