Debt Instrument, Principal Amount [Abstract]

No definition available.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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- Definition

The carrying value as of the balance sheet date of the noncurrent portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=99376301&loc=d3e1336-112600

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=99376301&loc=d3e1314-112600

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ References

+ Details

Name:	us-gaap_UnsecuredLongTermDebt
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Long-Term Debt (Schedule of Long-Term Debt) (Details) - USD ($)	1 Months Ended	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Principal
Notes payable		$ 114,975,200	$ 95,512,200
Line-of-credit		9,143,606	8,172,473
Total		124,118,806	103,684,673
Unamortized Debt Issuance Costs		299,175	313,315
Notes Payable
Principal
Notes payable		114,975,200	95,512,200
Unamortized Debt Issuance Costs		$ 299,175	$ 313,315
Roanoke Gas \| Unsecured Senior Notes \| Unsecured senior notes payable, at 4.26%, due on September 18, 2034
Debt Instrument [Line Items]
Stated rate		4.26%	4.26%
Principal
Notes payable		$ 30,500,000	$ 30,500,000
Unamortized Debt Issuance Costs		135,157	144,811
Roanoke Gas \| Unsecured Debt \| Unsecured term note payable, at 30-day LIBOR plus 0.90%, November 1, 2021
Principal
Notes payable		7,000,000	7,000,000
Unamortized Debt Issuance Costs		$ 3,613	$ 6,948
Roanoke Gas \| Unsecured Debt \| Unsecured term note payable, at 30-day LIBOR plus 0.90%, November 1, 2021 \| 30-day LIBOR
Debt Instrument [Line Items]
Variable rate basis points (as a percent)		0.90%	0.90%
Roanoke Gas \| Unsecured Debt \| Unsecured term notes payable, at 3.58% due on October 2, 2027
Debt Instrument [Line Items]
Stated rate		3.58%	3.58%
Principal
Notes payable		$ 8,000,000	$ 8,000,000
Unamortized Debt Issuance Costs		$ 33,712	$ 38,528
Roanoke Gas \| Unsecured Debt \| Unsecured term notes payable at 4.41%, due on March 28, 2031
Debt Instrument [Line Items]
Stated rate		4.41%	4.41%
Principal
Notes payable		$ 10,000,000	$ 10,000,000
Unamortized Debt Issuance Costs		$ 32,892	36,272
Roanoke Gas \| Unsecured Debt \| Unsecured term notes payable at 3.60%, due on December 6, 2029
Debt Instrument [Line Items]
Stated rate	3.60%	3.60%
Principal
Notes payable		$ 10,000,000	0
Unamortized Debt Issuance Costs		32,585	0
Roanoke Gas \| Line of Credit \| Line-of-credit, at 30-day LIBOR plus 1.00%, due March 31, 2022
Principal
Line-of-credit		9,143,606	8,172,473
Unamortized Debt Issuance Costs		$ 0	0
Roanoke Gas \| Line of Credit \| Line-of-credit, at 30-day LIBOR plus 1.00%, due March 31, 2022 \| 30-day LIBOR
Debt Instrument [Line Items]
Variable rate basis points (as a percent)		1.00%
RGC Midstream, LLC \| Unsecured Debt \| Unsecured term notes payable, at 30-day LIBOR plus 1.35% due December 29, 2022
Principal
Notes payable		$ 25,475,200	16,012,200
Unamortized Debt Issuance Costs		$ 38,728	$ 59,504
RGC Midstream, LLC \| Unsecured Debt \| Unsecured term notes payable, at 30-day LIBOR plus 1.35% due December 29, 2022 \| 30-day LIBOR
Debt Instrument [Line Items]
Variable rate basis points (as a percent)	1.35%	1.35%	1.35%
RGC Midstream, LLC \| Unsecured Debt \| Unsecured term note payable, at 30-day LIBOR plus 1.15%, due June 12, 2026
Principal
Notes payable		$ 14,000,000	$ 14,000,000
Unamortized Debt Issuance Costs		$ 13,844	$ 16,252
RGC Midstream, LLC \| Unsecured Debt \| Unsecured term note payable, at 30-day LIBOR plus 1.15%, due June 12, 2026 \| 30-day LIBOR
Debt Instrument [Line Items]
Variable rate basis points (as a percent)		1.15%	1.15%
RGC Midstream, LLC \| Unsecured Debt \| Unsecured term note payable, at 30-day LIBOR plus 1.20%, due June 1, 2024
Principal
Notes payable		$ 10,000,000	$ 10,000,000
Unamortized Debt Issuance Costs		$ 8,644	$ 11,000
RGC Midstream, LLC \| Unsecured Debt \| Unsecured term note payable, at 30-day LIBOR plus 1.20%, due June 1, 2024 \| 30-day LIBOR
Debt Instrument [Line Items]
Variable rate basis points (as a percent)		1.20%	1.20%