Reinsurance (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Short Duration Contracts Premium And Fees [Abstract]
Direct	$ 23,954	$ 17,300	$ 16,492
Assumed	382	158	496
Ceded	(217)	(185)	(187)
Total short duration	24,119	17,273	16,801
Long Duration Contracts Premium And Fees [Abstract]
Direct	2,234	1,919	1,687
Assumed	86	36	36
Ceded: Individual life insurance and annuity business sold	(186)	(203)	(195)
Ceded: Other	(66)	(59)	(55)
Total long duration	2,068	1,693	1,473
Total premiums and fees	26,187	18,966	18,274
Reinsurance Recoveries [Abstract]
Individual life insurance and annuity business sold	316	310	321
Other	201	213	156
Total	517	523	477
Ceded Credit Risk [Line Items]
Reinsurance recoverables	6,256	6,256
Great American Life Insurance Company [Member]
Ceded Credit Risk [Line Items]
Reinsurance recoverables	402
Reinsurance recoverable percent secured	100.00%
Prudential Retirement Insurance And Annuity Company [Member]
Ceded Credit Risk [Line Items]
Reinsurance recoverables	1,300	1,600
Reinsurance recoverable percent secured	100.00%
The Lincoln National Life Insurance Company And Lincoln Life And Annuity Of New York [Member]
Ceded Credit Risk [Line Items]
Reinsurance recoverables	4,000	4,200
Various Reinsurers Used In The Ordinary Course Of Business [Member]
Ceded Credit Risk [Line Items]
Reinsurance recoverables	345
Reinsurance recoverable percent secured	16.00%
Reserve Held For Ceded Reinsurance Recoverable Ongoing Operations	4
Enstar Group Limited [Member]
Ceded Credit Risk [Line Items]
Reinsurance recoverables	170
Reinsurance recoverable percent secured	97.00%
Reserve Held For Ceded Reinsurance Recoverable Ongoing Operations	$ 1

Name:	ci_LongDurationContractsPremiumAndFeesAbstract
Namespace Prefix:	ci_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Premiums and fees on long duration contracts assumed by the Company from other insurance companies.

+ References

No definition available.

+ Details

Name:	ci_PremiumsAndFeesAssumedLongDuration
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Premiums and fees on short duration contracts assumed by the Company from other insurance companies.

+ References

No definition available.

+ Details

Name:	ci_PremiumsAndFeesAssumedShortDuration
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Premiums and fees on long duration contracts from the sold Individual life insurance and annuity business ceded by the Company to Lincoln National Life Insurance.

+ References

No definition available.

+ Details

Name:	ci_PremiumsAndFeesCededIndividualLifeInsuranceAndAnnuityBusinessSoldLongDuration
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Premiums and fees on long duration contracts from other businesses ceded by the Company to other insurance companies.

+ References

No definition available.

+ Details

Name:	ci_PremiumsAndFeesCededOtherLongDuration
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Premiums and fees on short duration contracts ceded by the Company to other insurance companies.

+ References

No definition available.

+ Details

Name:	ci_PremiumsAndFeesCededShortDuration
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Premiums and fees on long duration contracts directly written by the Company.

+ References

No definition available.

+ Details

Name:	ci_PremiumsAndFeesDirectLongDuration
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Premiums and fees on short duration contracts directly written by the Company.

+ References

No definition available.

+ Details

Name:	ci_PremiumsAndFeesDirectShortDuration
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Premiums and fees on long duration contracts net of ceded and assumed amounts.

+ References

No definition available.

+ Details

Name:	ci_PremiumsAndFeesLongDuration
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Premiums and fees on short duration contracts net of ceded and assumed amounts.

+ References

No definition available.

+ Details

Name:	ci_PremiumsAndFeesShortDuration
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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. Total fees and commissions earned from providing services such as leasing of space or maintaining: (1) depositor accounts; (2) transfer agent; (3) fiduciary and trust; (4) brokerage and underwriting; (5) mortgage; (6) credit cards; (7) correspondent clearing; and (8) other such services and activities performed for others. Total fees and commissions earned from providing services such as leasing of space or maintaining: (1) depositor accounts; (2) transfer agent; (3) fiduciary and trust; (4) brokerage and underwriting; (5) mortgage; (6) credit cards; (7) correspondent clearing; and (8) other such services and activities performed for others.

+ References

No definition available.

+ Details

Name:	ci_PremiumsEarnedNetFeesAndCommissions
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of reinsurance recoverables secured by assets in trust or letters of credit.

+ References

No definition available.

+ Details

Name:	ci_ReinsuranceRecoverablePercentSecured
Namespace Prefix:	ci_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	ci_ReinsuranceRecoveriesAbstract
Namespace Prefix:	ci_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Reinsurance recoveries from other operations that are netted against Benefits and Expenses in the Company's Consolidated Statements of Income

+ References

No definition available.

+ Details

Name:	ci_ReinsuranceRecoveriesOther
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reinsurance recoveries from the Individual Life Insurance and Annuity business sold that are netted against Benefits and Expenses in the Company's Consolidated Statements of Income

+ References

No definition available.

+ Details

Name:	ci_ReinsuranceRecoveriesSoldBusiness
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Total reinsurance recoveries that are netted against Benefits and expenses in the Company's Consolidated Statements of Income.

+ References

No definition available.

+ Details

Name:	ci_ReinsuranceRecoveriesTotal
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reserve for uncollectible ceded reinsurance - ongoing operations

+ References

No definition available.

+ Details

Name:	ci_ReserveHeldForCededReinsuranceRecoverableOngoingOperations
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	ci_ShortDurationContractsPremiumAndFeesAbstract
Namespace Prefix:	ci_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

The known and estimated amount recoverable as of the balance sheet date from reinsurers for claims paid or incurred by the ceding insurer and associated claims settlement expenses, including estimated amounts for claims incurred but not reported, and policy benefits, net of any related valuation allowance.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.(a),6)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 7

-Section 03

-Paragraph 6

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 113

-Paragraph 14, 16, 27, 113

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 20

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6824-158387

+ Details

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