Note 17 - Leases (Tables)

12 Months Ended

Sep. 30, 2022

Notes Tables

Schedule of Operating Lease Cost, Cash Flow and Non Cash Information [Table Text Block]

	Spire						Spire Missouri						Spire Alabama
	2022		2021		2020		2022		2021		2020		2022		2021		2020
Operating lease cost, including amounts capitalized	$	7.4	$	7.2	$	8.7	$	0.5	$	0.4	$	0.5	$	2.1	$	2.1	$	3.5
Cash flow and noncash information about operating leases:
Operating cash flows representing cash paid for amounts included in the measurement of lease liabilities		7.3		7.2		8.5		0.5		0.4		0.5		2.1		2.1		3.3
Right-of-use assets obtained in exchange for lease liabilities		24.6		—		71.1		1.1		—		2.1		23.5		—		10.0

Schedule of Balance Sheet and Weighted Average Information About Operating Leases [Table Text Block]

	Spire						Spire Missouri						Spire Alabama
	2022			2021			2022			2021			2022			2021
Right-of-use assets	$	73.7		$	60.4		$	1.7		$	1.4		$	20.2		$	4.8
Lease liabilities, current		6.5			6.5			0.4			0.3			1.9			1.9
Lease liabilities, noncurrent		73.7			53.7			1.5			1.0			24.6			2.7
Weighted-average remaining lease term (in years)		15.0			15.3			5.1			4.5			14.3			2.3
Weighted-average discount rate		4.1	%		4.2	%		2.2	%		2.5	%		3.7	%		2.2	%

Lessee, Operating Lease, Liability, Maturity [Table Text Block]

	Spire			Spire Missouri			Spire Alabama
2023	$	6.7		$	0.4		$	1.9
2024		7.3			0.5			2.1
2025		7.4			0.4			2.1
2026		7.3			0.3			2.2
2027		7.3			0.2			2.3
Thereafter		72.8			0.2			24.1
Total undiscounted lease payments		108.8			2.0			34.7
Less present value discount		(28.6	)		(0.1	)		(8.2	)
Total current and noncurrent lease liabilities	$	80.2		$	1.9		$	26.5