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v3.23.1

Note 10 - Derivative Instruments and Hedging Activities (Details Textual) MMBTU in Millions, $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Sep. 30, 2021 USD ($) | Jun. 30, 2021 USD ($) | Mar. 31, 2020 USD ($) | Sep. 30, 2022 USD ($) MMBTU
Nonmonetary Notional Amount of Natural Gas Derivative Contracts Not Designated As Normal Purchases Or Normal Sales (Millions of British Thermal Unit) | MMBTU |  |  |  |  |  | 492.2
Notional Amount of Non Exchange Traded Natural Gas Commodity Contracts To Be Settled In Next Twelve Months (Millions of British Thermal Unit) | MMBTU |  |  |  |  |  | 347.8
Notional Amount of Non Exchange Traded Natural Gas Commodity Contracts To Be Settled In Year Two (Millions of British Thermal Unit) | MMBTU |  |  |  |  |  | 88.8
Notional Amount of Non Exchange Traded Natural Gas Commodity Contracts To Be Settled In Year Three (Millions of British Thermal Unit) | MMBTU |  |  |  |  |  | 47.5
Notional Amount of Non Exchange Traded Natural Gas Commodity Contracts To Be Settled In Year Four (Millions of British Thermal Unit) | MMBTU |  |  |  |  |  | 7.0
Notional Amount of Non Exchange Traded Natural Gas Commodity Contracts To Be Settled In Year Five (Millions of British Thermal Unit) | MMBTU |  |  |  |  |  | 1.1
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax |  |  |  |  |  | $ 63.6
Other Receivable from Broker-Dealer and Clearing Organization |  |  | $ 40.8 |  |  | $ 49.8
Spire Missouri [Member] |  |  |  |  |  |
Nonmonetary Notional Amount of Other Price Mitigation in Place Not Designated As Normal Purchases Or Normal Sales (Millions of British Thermal Unit) | MMBTU |  |  |  |  |  | 23.4
Other Receivable from Broker-Dealer and Clearing Organization |  |  | $ 40.3 |  |  | $ 24.0
Interest Rate Swap Agreement Two [Member] |  |  |  |  |  |
Derivative, Term of Contract (Year) |  |  |  |  | 10 years |
Interest Rate Swap Agreement Four [Member] |  |  |  |  |  |
Derivative, Notional Amount |  |  |  |  | $ 75.0 |
Derivative, Gain (Loss) on Derivative, Net, Total |  |  |  |  |  | 9.8
Interest Rate Swap Agreement Four [Member] | Minimum [Member] |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  |  |  | 0.934% |
Interest Rate Swap Agreement Four [Member] | Maximum [Member] |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  |  |  | 1.2975% |
Interest Rate Swap Agreement Five [Member] |  |  |  |  |  |
Derivative, Term of Contract (Year) |  |  |  | 10 years |  |
Derivative, Notional Amount |  |  |  | $ 150.0 |  |
Derivative, Gain (Loss) on Derivative, Net, Total |  |  |  |  |  | 17.9
Interest Rate Swap Agreement Five [Member] | Minimum [Member] |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  |  | 2.008% |  |
Interest Rate Swap Agreement Five [Member] | Maximum [Member] |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  |  | 2.1075% |  |
Interest Rate Swap Agreement Six [Member] |  |  |  |  |  |
Derivative, Term of Contract (Year) |  |  | 10 years |  |  |
Derivative, Fixed Interest Rate |  |  | 1.597% |  |  |
Derivative, Notional Amount |  |  | $ 50.0 |  |  |
Interest Rate Swap Agreement Seven [Member] |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  | 1.821% |  |  |
Derivative, Notional Amount |  |  | $ 50.0 |  |  |
Derivative, Gain (Loss) on Derivative, Net, Total |  |  |  |  |  | 5.7
Interest Rate Swap Agreement Eight [Member] |  |  |  |  |  |
Derivative, Term of Contract (Year) |  | 10 years |  |  |  |
Derivative, Fixed Interest Rate |  | 1.4918% |  |  |  |
Derivative, Notional Amount |  | $ 50.0 |  |  |  |
Derivative, Gain (Loss) on Derivative, Net, Total |  |  |  |  |  | 7.0
Interest Rate Swap Agreement Nine [Member] |  |  |  |  |  |
Derivative, Term of Contract (Year) | 10 years |  |  |  |  |
Derivative, Notional Amount | $ 150.0 |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net, Total |  |  |  |  |  | $ 16.2
Interest Rate Swap Agreement Nine [Member] | Minimum [Member] |  |  |  |  |  |
Derivative, Fixed Interest Rate | 1.6475% |  |  |  |  |
Interest Rate Swap Agreement Nine [Member] | Maximum [Member] |  |  |  |  |  |
Derivative, Fixed Interest Rate | 1.746% |  |  |  |  |

X
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- Definition Aggregate notional amount of other price mitigation in place not designated as normal purchases or normal sales with notional amounts expressed in nonmonetary units. + References No definition available. + Details
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- Definition Notional amount of non-exchange traded natural gas commodity contracts to be settled in next twelve months. + References No definition available. + Details
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- Definition Amount, after tax, of accumulated gain (loss) on derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482790/220-10-45-11 + Details
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