Reinsurance - GMIB Guarantees (Details) - Guarantee Type, Other [Member] - Guaranteed Minimum Income Benefit [Member] - Variable Annuity [Member] $ in Millions	Dec. 31, 2016 USD ($)
Guarantee Obligations [Line Items]
Underlying mutual fund investment values	$ 810
Maximum Exposure, Undiscounted	703
Minimum [Member]
Guarantee Obligations [Line Items]
Current Carrying Value	$ 703

The value of investments in mutual funds assumed in calculating the reporting entity's maximum potential future payments for guarantees related to reinsured benefits.

No definition available.

+ Details

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

- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

+ Details

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Balance Type:	credit
Period Type:	instant

- Details

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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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Namespace Prefix:
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- Details

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