XML 20 R46.htm IDEA: XBRL DOCUMENT v2.4.1.9
Employee Benefit Plans Other Employee Matters (Details) (Employees Subject To Collective Bargaining Agreements [Member], Labor Force Concentration Risk [Member])
12 Months Ended
Dec. 31, 2014
Number of Employees, Total [Member]  
Concentration Risk [Line Items]  
Concentration Risk, Percentage 26.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_CollectiveBargainingArrangementAxis
= cerc_EmployeesSubjectToCollectiveBargainingAgreementsMember
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_NumberOfEmployeesTotalMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_LaborForceConcentrationRiskMember
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member]  
Concentration Risk [Line Items]  
Concentration Risk, Percentage 14.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_CollectiveBargainingArrangementAxis
= cerc_EmployeesSubjectToCollectiveBargainingAgreementsMember
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_WorkforceSubjectToCollectiveBargainingArrangementsExpiringWithinOneYearMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_LaborForceConcentrationRiskMember