Notes Payable and Credit Agreements (Tables)

12 Months Ended

Sep. 30, 2025

Debt Disclosure [Abstract]

Schedule of Short-Term Debt

Information about short-term borrowings, including Spire Missouri’s and Spire Alabama’s borrowings from Spire, is presented in the following table. As of September 30, 2025, $741.0 of Spire’s short-term borrowings were used to support lending to the Utilities.

	Spire			Spire				Spire
	(Parent Only)			Missouri				Alabama			Spire
	CP				Spire			Spire			Consol-
	Program				Note			Note			idated
Year Ended September 30, 2025
Highest borrowings outstanding	$	1,348.0			$	615.0		$	130.6		$	1,348.0
Lowest borrowings outstanding		896.0				299.5			1.2			896.0
Weighted average borrowings		1,085.7				482.6			50.8			1,085.7
Weighted average interest rate		4.5	%			4.7	%		4.7	%		4.5	%
As of September 30, 2025
Borrowings outstanding	$	1,317.0			$	566.3		$	130.1		$	1,317.0
Weighted average interest rate		4.4	%			4.4	%		4.4	%		4.4	%
As of September 30, 2024
Borrowings outstanding	$	947.0			$	495.3		$	48.4		$	947.0
Weighted average interest rate		5.2	%			5.2	%		5.2	%		5.2	%

For additional information regarding the pending acquisition of Tennessee natural gas business from Piedmont Natural Gas, see Note 18 – Business Combinations, which is supported by a fully committed bridge financing facility discussed therein.