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
Subsequent Event [Line Items]
Senior notes, at par	$ 429cnc_SeniorNotesAtPar		$ 431cnc_SeniorNotesAtPar
Derivative, Notional Amount		300invest_DerivativeNotionalAmount		250invest_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					200cnc_SeniorNotesAtPar / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Derivative, Notional Amount					$ 200invest_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

X

- 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

X

- 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

X

- 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

X

- 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

X

- Details

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

X

- Details

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

X

- Details

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