Debt instrument and equity units.

No definition available.

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- Definition

Short-term borrowings used to support lending to Utilities

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

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+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The average effective interest rate during the reporting period.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

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- Definition

Description of the payment terms of the debt instrument (for example, whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment.

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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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Financing - Additional Information (Details) - USD ($)		1 Months Ended	6 Months Ended
Financing - Additional Information (Details) - USD ($)	Dec. 07, 2021	Mar. 31, 2021	Mar. 31, 2022
Spire
Debt Instrument And Equity Units [Line Items]
Stated Interest rate			0.50%
Spire Missouri
Debt Instrument And Equity Units [Line Items]
Stated Interest rate			0.80%
Spire Missouri \| Bonds due December 2, 2024
Debt Instrument And Equity Units [Line Items]
Interest rate	0.50%
Long-term debt	$ 300,000,000.0
Stated Interest rate	8.00%
Debt instrument, maturity date	Dec. 02, 2024
Debt instrument, payment terms			Interest is payable quarterly
Commercial Paper Notes
Debt Instrument And Equity Units [Line Items]
Debt amount			$ 975,000,000.0
Debt term			365 days
Commercial Paper Notes \| Spire
Debt Instrument And Equity Units [Line Items]
Short-term borrowings used to support lending to Utilities			$ 496,600,000
Stated Interest rate			0.40%
Unsecured Term Loan \| Spire Missouri
Debt Instrument And Equity Units [Line Items]
Debt amount		$ 250,000,000.0
Debt term		364 days
Unsecured Term Loan \| Spire Missouri \| LIBOR
Debt Instrument And Equity Units [Line Items]
Interest rate		0.65%