Note 6 - Other Investments (Details Textual) - RGC Midstream LLC [Member] - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Mar. 31, 2022	Jun. 30, 2023
MVP Southgate Investment [Member]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		1.00%
MVP [Member]
Equity Method Investment, Ownership Percentage		1.00%
Number of Gate Stations, Suspended Accruing of Afudc		2
Long Term Investment, Other than Temporary Impairment	$ 39.8	$ 15.3

The amount of other than temporary impairment (OTTI) losses on long term investments.

No definition available.

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Namespace Prefix:	rgco_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the number of gate stations that suspended the accruing of AFUDC.

+ References

No definition available.

+ Details

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Namespace Prefix:	rgco_
Data Type:	xbrli:integerItemType
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Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

+ Details

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- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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