Commitments and Contingencies (Schedule of Volumetric Obligations) (Details)	Sep. 30, 2020 MMBTU
Commitments and Contingencies Disclosure [Abstract]
2020-2021	2,090,972
2021-2022	295,866
Total	2,386,838

Energy Purchase Volume Obligation Due In Next Twelve Months

No definition available.

Name:	rgco_EnergyPurchaseObligationDueInNextTwelveMonths
Namespace Prefix:	rgco_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant