Summary of Significant Accounting Policies (Components of Utility Plant) (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Distribution and transmission	$ 227,753,620	$ 209,171,339
LNG storage	14,798,453	13,417,077
General and miscellaneous	15,790,299	15,198,548
Total utility plant in service	$ 258,342,372	$ 237,786,964

Period end amount of other property, plant and equipment (PPE) owned (but not classified elsewhere) by the public utility.

No definition available.

Name:	rgco_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipmentGross
Namespace Prefix:	rgco_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant