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EMPLOYEE BENEFIT PLAN (Detail Textuals) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Multiple Employers Retirement Income Plan      
Multiemployer Plans [Line Item]      
Contribution by employer for retirement income plan $ 850,000us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= res_MultipleEmployerRetirementIncomePlanMember
$ 765,000us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= res_MultipleEmployerRetirementIncomePlanMember
 
Non-qualified Supplemental Retirement Plan ("SERP")      
Multiemployer Plans [Line Item]      
SERP assets $ 16,695,000us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember
  $ 16,491,000us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember