v2.4.1.9
Fair Value Measurements (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Fair Value Disclosures [Abstract]    
Transfers from Level I to Level II $ 14us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount  
Transfers from Level II to Level I 1us-gaap_FairValueAssetsLevel2ToLevel1TransfersAmount  
Life insurance contracts and cost-method investments $ 84cnc_LifeInsuranceContractsAndCostMethodInvestmentsFairValueDisclosure $ 37cnc_LifeInsuranceContractsAndCostMethodInvestmentsFairValueDisclosure