v2.4.1.9
Income Taxes (Reconciliation Of The Tax Provision At The U.S. Federal Statutory Rate To The Provision For Income Taxes) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Income Tax Disclosure [Abstract]      
Earnings from continuing operations, before income tax expense $ 457us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments $ 269us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments $ 123us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
(Earnings) loss attributable to flow through noncontrolling interest 4cnc_LessFlowThroughNoncontrollingInterest (1)cnc_LessFlowThroughNoncontrollingInterest 2cnc_LessFlowThroughNoncontrollingInterest
Earnings from continuing operations, less noncontrolling interest, before income tax expense 461cnc_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsLessNoncontrollingInterest 268cnc_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsLessNoncontrollingInterest 125cnc_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsLessNoncontrollingInterest
Tax provision at the U.S. federal statutory rate 162us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate 94us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate 44us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate
State income taxes, net of federal income tax benefit 6us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes 3us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes (2)us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes
Nondeductible compensation 1us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost 12us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost 1us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost
Benefit from reversal of prior years impact of 162(m)(6) regulations (14)cnc_Benefitfromreversalofprioryearsimpactof162m6regulations 0cnc_Benefitfromreversalofprioryearsimpactof162m6regulations 0cnc_Benefitfromreversalofprioryearsimpactof162m6regulations
ACA Health Insurer Fee 44cnc_ACAHealthInsurerFee 0cnc_ACAHealthInsurerFee 0cnc_ACAHealthInsurerFee
Nondeductible goodwill impairment 0us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses 0us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses 8us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses
Other, net (3)us-gaap_IncomeTaxReconciliationOtherReconcilingItems (2)us-gaap_IncomeTaxReconciliationOtherReconcilingItems (4)us-gaap_IncomeTaxReconciliationOtherReconcilingItems
Income tax expense $ 196us-gaap_IncomeTaxExpenseBenefit $ 107us-gaap_IncomeTaxExpenseBenefit $ 47us-gaap_IncomeTaxExpenseBenefit