Revenue - Additional Information (Details) $ in Millions	Feb. 28, 2021 USD ($)
Spire Missouri
Disaggregation Of Revenue [Line Items]
Regulatory liability with a reduction in revenue	$ 25.0

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.

No definition available.

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Balance Type:	na
Period Type:	duration