Subsequent Event	12 Months Ended
Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Event	18. SUBSEQUENT EVENT On November 19, 2019, the Missouri Western Court of Appeals issued rulings (“ISRS rulings”) that determined certain capital investments in 2016 through 2018 were not eligible for recovery under the Infrastructure System Replacement Surcharge. The ISRS rulings upheld appeals by the Office of Public Counsel that contested recovery of portions of Spire Missouri’s ISRS, overturned three prior MoPSC decisions, and ordered refunds to customers of certain amounts deemed not eligible for ISRS recovery. Ultimately, the MoPSC will define its process to enact the decision and the appropriate refund, if any, at a later date should the decision ultimately stand. Spire Missouri strongly disagrees with the ISRS rulings, plans to vigorously defend its position, and is evaluating its legal and regulatory options in response. Spire Missouri plans to continue the appeal process, which will stay the effectiveness of the ISRS rulings. Spire Missouri has recorded an estimate of the maximum impact of the ISRS rulings based on its interpretation of the rulings and evidence available at the time of this filing. As of September 30, 2019, Spire Missouri recorded an estimated $12.2 regulatory liability for this matter by reducing revenue for fiscal year 2019. There are two components of this provision. The first relates to a $4.2 refund ordered by the ISRS rulings for amounts collected prior to the last rate case, after which recoveries of related authorized revenues became part of base rates that went into effect in April 2018. The second component relates to an estimate of $8.0 for revenues associated with the June 2018 ISRS filing that was approved by the MoPSC in September 2018. The after-tax impact of the provision reduced net income by $9.3, or $0.18 per diluted share. Additional ISRS revenues are currently under appeal related to the January 2019 ISRS filings with annual authorized revenue of $12.4. The estimated amount earned in fiscal year 2019 under this ISRS order was $4.6. Additionally, in future periods Spire Missouri will evaluate the need for an adjustment to the provision based upon new information and further developments.

Subsequent Event

12 Months Ended

Sep. 30, 2019

18. SUBSEQUENT EVENT

On November 19, 2019, the Missouri Western Court of Appeals issued rulings (“ISRS rulings”) that determined certain capital investments in 2016 through 2018 were not eligible for recovery under the Infrastructure System Replacement Surcharge. The ISRS rulings upheld appeals by the Office of Public Counsel that contested recovery of portions of Spire Missouri’s ISRS, overturned three prior MoPSC decisions, and ordered refunds to customers of certain amounts deemed not eligible for ISRS recovery. Ultimately, the MoPSC will define its process to enact the decision and the appropriate refund, if any, at a later date should the decision ultimately stand.

Spire Missouri strongly disagrees with the ISRS rulings, plans to vigorously defend its position, and is evaluating its legal and regulatory options in response. Spire Missouri plans to continue the appeal process, which will stay the effectiveness of the ISRS rulings. Spire Missouri has recorded an estimate of the maximum impact of the ISRS rulings based on its interpretation of the rulings and evidence available at the time of this filing. As of September 30, 2019, Spire Missouri recorded an estimated $12.2 regulatory liability for this matter by reducing revenue for fiscal year 2019. There are two components of this provision. The first relates to a $4.2 refund ordered by the ISRS rulings for amounts collected prior to the last rate case, after which recoveries of related authorized revenues became part of base rates that went into effect in April 2018. The second component relates to an estimate of $8.0 for revenues associated with the June 2018 ISRS filing that was approved by the MoPSC in September 2018. The after-tax impact of the provision reduced net income by $9.3, or $0.18 per diluted share.

Additional ISRS revenues are currently under appeal related to the January 2019 ISRS filings with annual authorized revenue of $12.4. The estimated amount earned in fiscal year 2019 under this ISRS order was $4.6. Additionally, in future periods Spire Missouri will evaluate the need for an adjustment to the provision based upon new information and further developments.