v2.4.1.9

Subsequent Events (Details) (USD $) In Millions, unless otherwise specified | Dec. 31, 2014 | Apr. 30, 2014 | Dec. 31, 2013 | May 31, 2011 | Jan. 31, 2015
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Subsequent Event [Line Items] |  |  |  |  |
Senior notes, at par | $ 429 cnc_SeniorNotesAtPar |  | $ 431 cnc_SeniorNotesAtPar |  |
Derivative, Notional Amount |  | 300 invest_DerivativeNotionalAmount |  | 250 invest_DerivativeNotionalAmount |
Subsequent Event [Member] |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |
Variable rate of swap, percentage |  |  |  |  | 2.88%us-gaap_DerivativeVariableInterestRate / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Senior notes, at par |  |  |  |  | 200 cnc_SeniorNotesAtPar / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Derivative, Notional Amount |  |  |  |  | $ 200 invest_DerivativeNotionalAmount / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Interest rate on notes, percentage |  |  |  |  | 4.75%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Celtic Insurance Company [Member] |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Parent |  |  |  |  | 25.00%cnc_Ownershippercentagesoldbyparent / us-gaap_SubsequentEventTypeAxis = cnc_CelticInsuranceCompanyMember

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- Definition Ownership percentage sold by parent + References No definition available. + Details
Name: | cnc_Ownershippercentagesoldbyparent
Namespace Prefix: | cnc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- Definition Senior Notes At Par + References No definition available. + Details
Name: | cnc_SeniorNotesAtPar
Namespace Prefix: | cnc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
Name: | invest_DerivativeNotionalAmount
Namespace Prefix: | invest_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Variable interest rate in effect as of the balance sheet date related to the interest rate derivative. + References No definition available. + Details
Name: | us-gaap_DerivativeVariableInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_SubsequentEventTypeAxis=cnc_CelticInsuranceCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |