v2.4.1.9

Short-Term And Long-Term Investments And Restricted Deposits (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 positions
Investments, Debt and Equity Securities [Abstract]
Percentage of investments in securities recorded at fair value that carry a rating by S&P or Moody's of AAA/Aaa	50.00%cnc_PercentageOfInvestmentsRecordedAtFairValueThatCarryRatingOfAaaOrAaa
Percentage of investments in securities recorded at fair value that carry a rating by S&P or Moody's of AA-/Aa3 or higher	62.00%cnc_PercentageOfInvestmentsRecordedAtFairValueThatCarryRatingOfAaMinusOrAa3OrHigher
Percentage of investments in securities recorded at fair value that carry a rating by S&P or Moody's of A-/A3 or higher	90.00%cnc_PercentageOfInvestmentsRecordedAtFairValueThatCarryRatingOfMinusOrA3OrHigher
Positions from which gross unrealized losses were generated	116cnc_PositionsFromWhichGrossUnrealizedLossesWereGenerated
Total number of positions	341cnc_Totalunrealizedinvestmentpositions
Income (Loss) from Equity Method Investments	$ 6us-gaap_IncomeLossFromEquityMethodInvestments

X

- Definition

The percentage of investments in securities recorded at fair value that carry a rating by Moody's or S&P of AAA/Aaa.

+ References

No definition available.

+ Details

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- Definition

The percentage of investments in securities recorded at fair value that carry a rating by Moody's or S&P of AA-/Aa3 or higher.

+ References

No definition available.

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- Definition

The percentage of investments in securities recorded at fair value that carry a rating by Moody's or S&P of A-/A3 or higher.

+ References

No definition available.

+ Details

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- Definition

Positions from which gross unrealized losses were generated

+ References

No definition available.

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- Definition

Total Unrealized Investment Positions

+ References

No definition available.

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X

- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 9

-Article 5



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.12)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688



Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 11

-Article 7

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