Supplemental Schedules of Oil and Gas Information (Details Textual) - bbl	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Oil and Condensate (Bbls) [Member]
Proved Developed and Undeveloped Reserves Production Royalty	30,191	16,421
Gas (MCF) [Member]
Proved Developed and Undeveloped Reserves Production Royalty	393,584	288,743

Company's share of production of proved reserves from net royalty interests.

No definition available.

Name:	rsrv_ProvedDevelopedAndUndevelopedReservesProductionRoyalty
Namespace Prefix:	rsrv_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	duration