v2.4.1.9

Stockholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified | 12 Months Ended | 1 Months Ended |
--- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Jan. 31, 2014 | Jul. 31, 2014 | Apr. 30, 2013 | Oct. 26, 2009
Class of Stock [Line Items] |  |  |  |  |  |  |
Preferred Stock, Shares Authorized | 10,000,000 us-gaap_PreferredStockSharesAuthorized | 10,000,000 us-gaap_PreferredStockSharesAuthorized |  |  |  |  |
Preferred Stock, Par or Stated Value Per Share | $ 0.001 us-gaap_PreferredStockParOrStatedValuePerShare | $ 0.001 us-gaap_PreferredStockParOrStatedValuePerShare |  |  |  |  |
Common stock, shares authorized to repurchase (in shares) |  |  |  |  |  |  | 8,000,000 us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Remaining number of shares available to be repurchased | 3,335,448 us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased |  |  |  |  |  |
Common stock repurchases (in shares) | 626,234 us-gaap_TreasuryStockSharesAcquired | 688,128 us-gaap_TreasuryStockSharesAcquired |  |  |  |  |
Payments for repurchase of common stock | $ 29 us-gaap_PaymentsForRepurchaseOfCommonStock | $ 19 us-gaap_PaymentsForRepurchaseOfCommonStock | $ 13 us-gaap_PaymentsForRepurchaseOfCommonStock |  |  |  |
Stock Issued During Period, Value, New Issues |  | 15 us-gaap_StockIssuedDuringPeriodValueNewIssues |  |  |  |  |
U.S. Medical Management [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired |  |  |  | 68.00%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired / us-gaap_BusinessAcquisitionAxis = cnc_U.S.MedicalManagementMember |  |  |
Stock Issued During Period, Shares, Acquisitions |  |  |  | 4,486,434 us-gaap_StockIssuedDuringPeriodSharesAcquisitions / us-gaap_BusinessAcquisitionAxis = cnc_U.S.MedicalManagementMember |  |  |
Community Health Solutions [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Stock Issued During Period, Shares, Acquisitions |  |  |  |  | 1,492,738 us-gaap_StockIssuedDuringPeriodSharesAcquisitions / us-gaap_BusinessAcquisitionAxis = cnc_CommunityHealthSolutionsMember |  |
Acaria Health [Member] |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired |  |  |  |  |  | 100.00%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired / us-gaap_BusinessAcquisitionAxis = cnc_AcariaHealthMember |
Stock Issued During Period, Shares, Acquisitions |  |  |  |  |  | 3,433,380 us-gaap_StockIssuedDuringPeriodSharesAcquisitions / us-gaap_BusinessAcquisitionAxis = cnc_AcariaHealthMember |
Stock Issued During Period, Shares, New Issues |  |  |  |  |  | 685,280 us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_BusinessAcquisitionAxis = cnc_AcariaHealthMember |
Stock Issued During Period, Value, New Issues |  |  |  |  |  | $ 15 us-gaap_StockIssuedDuringPeriodValueNewIssues / us-gaap_BusinessAcquisitionAxis = cnc_AcariaHealthMember |

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