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Benefit Plans - Additional Information (Detail)
12 Months Ended
Dec. 31, 2014
Defined Contribution Plan Disclosure [Line Items]  
Percentage of participant directed contributions to benefit plans 100.00%crr_DefinedBenefitPlanContributionsByPlanParticipantsPercentage
Maximum  
Defined Contribution Plan Disclosure [Line Items]  
Participants contribution percentage allowed to invest in Company's common stock 20.00%crr_DefinedContributionPlanPercentageOfParticipantsContributionToPurchaseCommonStock
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