v2.4.1.9
Acquisitions and Noncontrolling Interest Acquisitions (Details)
In Millions, except Share data, unless otherwise specified
12 Months Ended 1 Months Ended 1 Months Ended 12 Months Ended
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Dec. 31, 2012
USD ($)
Jul. 31, 2014
Ribera Salud [Member]
USD ($)
Dec. 31, 2014
Ribera Salud [Member]
USD ($)
Dec. 31, 2014
Ribera Salud [Member]
EUR (€)
Jul. 31, 2014
Community Health Solutions [Member]
USD ($)
Apr. 30, 2013
Acaria Health [Member]
USD ($)
Jan. 31, 2014
U.S. Medical Management [Member]
USD ($)
Dec. 31, 2014
U.S. Medical Management [Member]
USD ($)
Business Acquisition [Line Items]                    
Redeemable noncontrolling interest $ 148us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount $ 0us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount               $ 148us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
Business Acquisition, Percentage of Voting Interests Acquired               100.00%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
/ us-gaap_BusinessAcquisitionAxis
= cnc_AcariaHealthMember
68.00%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Total consideration             134us-gaap_BusinessCombinationConsiderationTransferred1
/ us-gaap_BusinessAcquisitionAxis
= cnc_CommunityHealthSolutionsMember
142us-gaap_BusinessCombinationConsiderationTransferred1
/ us-gaap_BusinessAcquisitionAxis
= cnc_AcariaHealthMember
213us-gaap_BusinessCombinationConsiderationTransferred1
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable             58us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable
/ us-gaap_BusinessAcquisitionAxis
= cnc_CommunityHealthSolutionsMember
75us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable
/ us-gaap_BusinessAcquisitionAxis
= cnc_AcariaHealthMember
133us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Business acquisition, cash paid             56us-gaap_PaymentsToAcquireBusinessesGross
/ us-gaap_BusinessAcquisitionAxis
= cnc_CommunityHealthSolutionsMember
67us-gaap_PaymentsToAcquireBusinessesGross
/ us-gaap_BusinessAcquisitionAxis
= cnc_AcariaHealthMember
80us-gaap_PaymentsToAcquireBusinessesGross
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Business Combination, Total Fair Value                 352cnc_BusinessCombinationTotalFairValue
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Redeemable Noncontrolling Interest, Equity, Fair Value                 139us-gaap_RedeemableNoncontrollingInterestEquityFairValue
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Acquisition of additional ownership 0us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries 0us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries 14us-gaap_PaymentsToAcquireAdditionalInterestInSubsidiaries              
Goodwill 754us-gaap_Goodwill 348us-gaap_Goodwill 256us-gaap_Goodwill       125us-gaap_Goodwill
/ us-gaap_BusinessAcquisitionAxis
= cnc_CommunityHealthSolutionsMember
92us-gaap_Goodwill
/ us-gaap_BusinessAcquisitionAxis
= cnc_AcariaHealthMember
280us-gaap_Goodwill
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles             9us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_BusinessAcquisitionAxis
= cnc_CommunityHealthSolutionsMember
35us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_BusinessAcquisitionAxis
= cnc_AcariaHealthMember
78us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Stock Issued During Period, Shares, Acquisitions             1,492,738us-gaap_StockIssuedDuringPeriodSharesAcquisitions
/ us-gaap_BusinessAcquisitionAxis
= cnc_CommunityHealthSolutionsMember
3,433,380us-gaap_StockIssuedDuringPeriodSharesAcquisitions
/ us-gaap_BusinessAcquisitionAxis
= cnc_AcariaHealthMember
4,486,434us-gaap_StockIssuedDuringPeriodSharesAcquisitions
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Business Combination, Contingent Consideration, Liability             20us-gaap_BusinessCombinationContingentConsiderationLiability
/ us-gaap_BusinessAcquisitionAxis
= cnc_CommunityHealthSolutionsMember
     
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High             28us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cnc_CommunityHealthSolutionsMember
     
Net deferred tax assests 144us-gaap_DeferredTaxAssetsNet 100us-gaap_DeferredTaxAssetsNet                
Stock Issued During Period, Shares, New Issues               685,280us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_BusinessAcquisitionAxis
= cnc_AcariaHealthMember
   
Stock Issued During Period, Value, New Issues   15us-gaap_StockIssuedDuringPeriodValueNewIssues           15us-gaap_StockIssuedDuringPeriodValueNewIssues
/ us-gaap_BusinessAcquisitionAxis
= cnc_AcariaHealthMember
   
Letters of Credit Outstanding, Amount         58us-gaap_LettersOfCreditOutstandingAmount
/ dei_LegalEntityAxis
= cnc_RiberaSaludMember
48us-gaap_LettersOfCreditOutstandingAmount
/ dei_LegalEntityAxis
= cnc_RiberaSaludMember
       
Percent of goodwill deductible for tax purposes             100.00%cnc_Percentofgoodwilldeductiblefortaxpurposes
/ us-gaap_BusinessAcquisitionAxis
= cnc_CommunityHealthSolutionsMember
  45.00%cnc_Percentofgoodwilldeductiblefortaxpurposes
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Payments to Acquire Interest in Joint Venture       17us-gaap_PaymentsToAcquireInterestInJointVenture
/ dei_LegalEntityAxis
= cnc_RiberaSaludMember
           
Equity Method Investment, Ownership Percentage       50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ dei_LegalEntityAxis
= cnc_RiberaSaludMember
           
Percent of future consideration issuable in shares                 50.00%cnc_Percentoffutureconsiderationissuableinshares
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
 
Proceeds from Noncontrolling Interests                   6us-gaap_ProceedsFromMinorityShareholders
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember
Reclassification to redeemable noncontrolling interest 9cnc_Reclassificationtoredeemablenoncontrollinginterest 0cnc_Reclassificationtoredeemablenoncontrollinginterest 0cnc_Reclassificationtoredeemablenoncontrollinginterest              
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest                   $ (6)us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest
/ us-gaap_BusinessAcquisitionAxis
= cnc_U.S.MedicalManagementMember