The amount of Forward Sales Agreements, Proceeds If Settled.

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- Definition

The amount of forward sales agreements shares

+ References

No definition available.

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- Definition

The amount of Forward Sales Agreements, Shares Settled

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No definition available.

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- Definition

Preferred share redemption cost

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No definition available.

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- Definition

Cash inflow from shares settled.

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No definition available.

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- Definition

Maximum aggregate offering price of sale of stock.

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No definition available.

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- Definition

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

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

The percentage rate used to calculate dividend payments on preferred stock.

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- Definition

Value of the difference between preference in liquidation and the par or stated values of the preferred shares.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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Shareholders' Equity - Additional Information (Details) - USD ($) $ in Millions		1 Months Ended		3 Months Ended			6 Months Ended
	Jan. 29, 2026	Feb. 28, 2026	Dec. 31, 2024	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2024	Mar. 31, 2026	Mar. 31, 2025	Jan. 12, 2026	Jan. 25, 2024
Subsidiary or Equity Method Investee [Line Items]
Preferred share redemption cost				$ 8.0	$ 0.0		$ 8.0	$ 0.0
6.375% Junior Subordinated Notes due 2086 [Member] \| Spire [Member]
Subsidiary or Equity Method Investee [Line Items]
Debt Instrument face amount									$ 200.0
Debt instrument interest rate stated percentage									6.375%
Series A Preferred Stock [Member]
Subsidiary or Equity Method Investee [Line Items]
Preferred stock percentage	5.90%	5.90%
Preferred share redemption cost		$ 8.0
Aggregate liquidation preference		$ 250.0
Depositary Shares [Member]
Subsidiary or Equity Method Investee [Line Items]
Preferred stock, shares outstanding		10,000,000
At The Market Program [Member]
Subsidiary or Equity Method Investee [Line Items]
Forward sales agreements, shares settled (in shares)			542,515
Proceeds from shares settled			$ 32.4
Sale of stock, maximum aggregate offering price				$ 123.6			$ 123.6			$ 200.0
Forward sales agreements, shares (in shares)						663,619
Forward sales agreements, proceeds if settled					$ 42.4			$ 42.4