Segment Information (Reconciliation of Segment Income to Consolidated) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Operating revenues	$ 9,780,289	$ 11,071,918	$ 22,437,731	$ 19,785,453	$ 9,851,869	$ 11,682,950	$ 25,274,959	$ 21,216,747	$ 63,075,391	$ 68,026,525
Depreciation									7,890,725	7,454,274
Operating income (loss)	(899,076)	$ 1,335,663	$ 6,999,616	$ 5,081,979	490,702	$ 1,637,057	$ 6,203,483	$ 3,264,222	12,518,182	11,595,464
Equity in earnings									4,814,874	3,020,348
Interest expense									4,099,158	3,618,551
Income before income taxes									13,870,194	11,349,143
Total assets	281,679,507				258,353,696				281,679,507	258,353,696
Gross additions to utility property									22,916,339	21,884,317
Gross investment in MVP and Southgate									7,864,859	20,965,907
Operating segments | Gas Utility
Segment Reporting Information [Line Items]
Operating revenues									62,408,925	67,306,260
Depreciation									7,890,725	7,454,274
Operating income (loss)									12,429,613	11,458,679
Equity in earnings									0	0
Interest expense									2,730,822	2,404,518
Income before income taxes									10,350,946	9,400,869
Total assets	211,994,364				195,969,019				211,994,364	195,969,019
Gross additions to utility property									22,916,339	21,884,317
Gross investment in MVP and Southgate									0	0
Operating segments | Investment in Affiliates
Segment Reporting Information [Line Items]
Operating revenues									0	0
Depreciation									0	0
Operating income (loss)									(220,194)	(153,149)
Equity in earnings									4,814,874	3,020,348
Interest expense									1,368,336	1,214,033
Income before income taxes									3,233,233	1,657,988
Total assets	57,660,105				47,429,368				57,660,105	47,429,368
Gross additions to utility property									0	0
Gross investment in MVP and Southgate									7,864,859	20,965,907
Parent and Other
Segment Reporting Information [Line Items]
Operating revenues									666,466	720,265
Depreciation									0	0
Operating income (loss)									308,763	289,934
Equity in earnings									0	0
Interest expense									0	0
Income before income taxes									286,015	290,286
Total assets	$ 12,025,038				$ 14,955,309				12,025,038	14,955,309
Gross additions to utility property									0	0
Gross investment in MVP and Southgate									$ 0	$ 0