v2.4.1.9

Goodwill And Intangible Assets (Schedule Of Changes In Goodwill By Operating Segment) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill [Line Items]
Goodwill	$ 754us-gaap_Goodwill	$ 348us-gaap_Goodwill	$ 256us-gaap_Goodwill
Goodwill, Acquired During Period	406us-gaap_GoodwillAcquiredDuringPeriod	92us-gaap_GoodwillAcquiredDuringPeriod
Medicaid Managed Care [Member]
Goodwill [Line Items]
Goodwill	276us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	151us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	151us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember
Goodwill, Acquired During Period	125us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember	0us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cnc_ManagedCareMember
Specialty Services [Member]
Goodwill [Line Items]
Goodwill	478us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	197us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	105us-gaap_Goodwill / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember
Goodwill, Acquired During Period	$ 281us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember	$ 92us-gaap_GoodwillAcquiredDuringPeriod / us-gaap_StatementBusinessSegmentsAxis = cnc_SpecialtyServicesMember

X

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

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

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=cnc_ManagedCareMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=cnc_SpecialtyServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: