Note 1 - Summary of Significant Accounting Policies (Details Textual) $ in Millions		3 Months Ended	12 Months Ended
Jan. 20, 2024 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Number of Reportable Segments		3	3
Restricted Cash		$ 20.5	$ 20.2	$ 14.2
MoGas Pipeline [Member] \| Subsequent Event [Member]
Payments to Acquire Businesses, Gross	$ 177.6
Other Income [Member]
Gain on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring		$ 8.2

The amount of gain reclassified into earnings in the period when cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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