Fair Value Measurements (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair Value Measurements [Abstract]
Life insurance contracts and cost-method investments	$ 24,094	$ 21,451

This element represents life insurance contracts and cost-method investments reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

No definition available.

Name:	cnc_LifeInsuranceContractsAndCostMethodInvestmentsFairValueDisclosure
Namespace Prefix:	cnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant