Note 2 - Revenue - Disaggregation of Revenue (Details) - USD ($)	3 Months Ended	6 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Total contracts with customers	$ 30,818,621	$ 35,258,265	$ 54,176,645	$ 68,682,849
Alternative revenue programs	1,840,755	2,771,392	2,902,083	2,629,143
Operating revenues	32,659,376	38,029,657	57,078,728	71,311,992
Oil and Gas [Member] \| Residential [Member]
Total contracts with customers	18,843,065	21,376,436	32,667,707	40,742,276
Oil and Gas [Member] \| Commercial [Member]
Total contracts with customers	10,398,801	12,025,056	18,240,077	24,044,169
Oil and Gas [Member] \| Transportation and Interruptible [Member]
Total contracts with customers	1,358,991	1,565,170	2,729,261	3,153,238
Product and Service, Other [Member]
Total contracts with customers	217,764	291,603	539,600	743,166
Gas Utility [Member]
Total contracts with customers	30,791,576	35,229,585	54,122,102	68,624,601
Alternative revenue programs	1,840,755	2,771,392	2,902,083	2,629,143
Operating revenues	32,632,331	38,000,977	57,024,185	71,253,744
Gas Utility [Member] \| Oil and Gas [Member] \| Residential [Member]
Total contracts with customers	18,843,065	21,376,436	32,667,707	40,742,276
Gas Utility [Member] \| Oil and Gas [Member] \| Commercial [Member]
Total contracts with customers	10,398,801	12,025,056	18,240,077	24,044,169
Gas Utility [Member] \| Oil and Gas [Member] \| Transportation and Interruptible [Member]
Total contracts with customers	1,358,991	1,565,170	2,729,261	3,153,238
Gas Utility [Member] \| Product and Service, Other [Member]
Total contracts with customers	190,719	262,923	485,057	684,918
Non-utility [Member]
Total contracts with customers	27,045	28,680	54,543	58,248
Alternative revenue programs	0	0	0	0
Operating revenues	27,045	28,680	54,543	58,248
Non-utility [Member] \| Oil and Gas [Member] \| Residential [Member]
Total contracts with customers	0	0	0	0
Non-utility [Member] \| Oil and Gas [Member] \| Commercial [Member]
Total contracts with customers	0	0	0	0
Non-utility [Member] \| Oil and Gas [Member] \| Transportation and Interruptible [Member]
Total contracts with customers	0	0	0	0
Non-utility [Member] \| Product and Service, Other [Member]
Total contracts with customers	$ 27,045	$ 28,680	$ 54,543	$ 58,248