SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ACCOUNTING FOR DERIVATIVES (DETAILS) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Fixed maturity securities that contain embedded derivatives classified as trading securities	$ 180.6	$ 196.6
Equity swap
Derivative Instruments, Gain (Loss) [Line Items]
Estimated fair value	156.2	54.4
Equity swap \| Investment income
Derivative Instruments, Gain (Loss) [Line Items]
Increase (decrease) in earnings due to sale of trading portfolio	177.5	25.5	(21.2)
Embedded derivative financial instruments
Derivative Instruments, Gain (Loss) [Line Items]
Increase (decrease) in earnings due to sale of trading portfolio	35.4	(2.8)	(20.4)
Fair value of derivatives	903.7	734.0
Embedded derivative associated with modified coinsurance agreement
Derivative Instruments, Gain (Loss) [Line Items]
Fair value of derivatives	$ 1.8	$ 5.5

Fix Maturity Securities That Contain Embedded Derivatives Classified as Trading Securities

No definition available.

Name:	cno_FixMaturitySecuritiesThatContainEmbeddedDerivativesClassifiedasTradingSecurities
Namespace Prefix:	cno_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5618551-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (a),(c),(d),(e)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

+ Details

Name:	us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Definition

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

+ Details

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

- Definition

Fair value of all derivative liabilities not designated as a hedging instrument.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611

+ Details

Name:	us-gaap_OtherDerivativesNotDesignatedAsHedgingInstrumentsLiabilitiesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant