v2.4.1.9

Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 segments	Dec. 31, 2013	Dec. 31, 2012
Number of reportable segments									2us-gaap_NumberOfReportableSegments
Premium and service revenues from external or internal customers	$ 4,725us-gaap_Revenues	$ 4,352us-gaap_Revenues	$ 4,023us-gaap_Revenues	$ 3,460us-gaap_Revenues	$ 2,932us-gaap_Revenues	$ 2,795us-gaap_Revenues	$ 2,611us-gaap_Revenues	$ 2,525us-gaap_Revenues	$ 16,560us-gaap_Revenues	$ 10,863us-gaap_Revenues	$ 8,110us-gaap_Revenues
Premium and service revenues									15,667cnc_PremiumAndServiceRevenues	10,526cnc_PremiumAndServiceRevenues	7,682cnc_PremiumAndServiceRevenues
Earnings (loss) from operations									464us-gaap_OperatingIncomeLoss	277us-gaap_OperatingIncomeLoss	108us-gaap_OperatingIncomeLoss
Total assets	5,838us-gaap_Assets				3,529us-gaap_Assets				5,838us-gaap_Assets	3,529us-gaap_Assets
External Customer [Member]
Premium and service revenues from external or internal customers									15,667us-gaap_Revenues / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember	10,526us-gaap_Revenues / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember	7,682us-gaap_Revenues / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember
Internal Customer [Member]
Premium and service revenues from external or internal customers									0us-gaap_Revenues / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember	0us-gaap_Revenues / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember	0us-gaap_Revenues / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember
Operating Segments [Member] | Medicaid Managed Care [Member]
Premium and service revenues									13,946cnc_PremiumAndServiceRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	9,782cnc_PremiumAndServiceRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	7,212cnc_PremiumAndServiceRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember
Earnings (loss) from operations									353us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	198us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	63us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember
Total assets	4,620us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember				2,817us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember				4,620us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	2,817us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	2,164us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember
Operating Segments [Member] | Specialty Services [Member]
Premium and service revenues									4,800cnc_PremiumAndServiceRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	2,932cnc_PremiumAndServiceRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	2,107cnc_PremiumAndServiceRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember
Earnings (loss) from operations									111us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	79us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	45us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember
Total assets	1,118us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember				596us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember				1,118us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	596us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	371us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember
Operating Segments [Member] | External Customer [Member] | Medicaid Managed Care [Member]
Premium and service revenues from external or internal customers									13,886us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	9,741us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	7,125us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember
Operating Segments [Member] | External Customer [Member] | Specialty Services [Member]
Premium and service revenues from external or internal customers									1,781us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	785us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	557us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember
Operating Segments [Member] | Internal Customer [Member] | Medicaid Managed Care [Member]
Premium and service revenues from external or internal customers									60us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	41us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	87us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember
Operating Segments [Member] | Internal Customer [Member] | Specialty Services [Member]
Premium and service revenues from external or internal customers									3,019us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	2,147us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	1,550us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_OperatingSegmentsMember / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember
Intersegment Eliminations [Member]
Premium and service revenues									(3,079)cnc_PremiumAndServiceRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember	(2,188)cnc_PremiumAndServiceRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember	(1,637)cnc_PremiumAndServiceRevenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember
Earnings (loss) from operations									0us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember	0us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember	0us-gaap_OperatingIncomeLoss / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember
Total assets	0us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember				0us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember				0us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember	0us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember	0us-gaap_Assets / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember
Intersegment Eliminations [Member] | External Customer [Member]
Premium and service revenues from external or internal customers									0us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember	0us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember	0us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_MajorCustomersAxis = cnc_ExternalCustomerMember
Intersegment Eliminations [Member] | Internal Customer [Member]
Premium and service revenues from external or internal customers									(3,079)us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember	(2,188)us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember	(1,637)us-gaap_Revenues / us-gaap_ConsolidationItemsAxis = us-gaap_IntersegmentEliminationMember / us-gaap_MajorCustomersAxis = cnc_InternalCustomerMember
Continuing Operations [Member]
Total assets	$ 5,738us-gaap_Assets / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentContinuingOperationsMember				$ 3,413us-gaap_Assets / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentContinuingOperationsMember				$ 5,738us-gaap_Assets / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentContinuingOperationsMember	$ 3,413us-gaap_Assets / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentContinuingOperationsMember	$ 2,535us-gaap_Assets / us-gaap_StatementOperatingActivitiesSegmentAxis = us-gaap_SegmentContinuingOperationsMember

X

- Definition

Premiums earned on the income statement for all insurance and reinsurance contracts after subtracting any amounts ceded to another insurer and adding premiums assumed from other insurers, plus aggregate revenue during the period from services rendered in the normal course of business, after deducting allowances and discounts. Premium and service revenues exclude Premium Tax Revenue.

+ References

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- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.18)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 7



Reference 4: http://www.xbrl.org/2003/role/presentationRef

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-Name Regulation S-X (SX)

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

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