Regulatory Matters (Details) - USD ($)		1 Months Ended		12 Months Ended
	Jan. 24, 2020	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Sep. 30, 2019
Public Utilities, General Disclosures [Line Items]
Regulatory assets		$ 13,815,561		$ 13,815,561	$ 13,712,737
Regulatory liabilities		10,729,082		$ 10,729,082	$ 10,934,434
Composite weighted-average depreciation rate				3.30%	3.31%
Effect of change in deprecation rate on depreciation expense					$ (32,570)
ESAC assets
Public Utilities, General Disclosures [Line Items]
Regulatory assets		525,000		$ 525,000
Excess deferred income taxes
Public Utilities, General Disclosures [Line Items]
Regulatory liabilities		10,729,082		$ 10,729,082	$ 10,934,434
Roanoke Gas
Public Utilities, General Disclosures [Line Items]
Additional write down of ESAC regulatory assets			$ 317,000
Rate refund repaid			$ 3,800,000
Regulatory liability, refund period (in years)				28 years
General Rate Case | Virginia State Corporate Commission (SCC) | Roanoke Gas
Public Utilities, General Disclosures [Line Items]
Approved non-gas rate increase	$ 7,250,000
Approved return on equity (as a percent)	9.44%
SAVE Plan and Rider Filing | Virginia State Corporate Commission (SCC) | Roanoke Gas
Public Utilities, General Disclosures [Line Items]
Approved non-gas rate increase		2,300,000
Refund from over-collected balance		$ 73,000