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After-tax charges (treated as a special item) related to the liquidation of Penn Treaty Network America Insurance Company, together with its subsidiary American Network Insurance Company (collectively 'Penn Treaty', a long-term care insurance carrier), triggering guaranty fund coverage and accrual of a liability. Special items are excluded from the calculation of 'adjusted income (loss) from operations' because management believes they are not representative of the underlying results of operations. This is generally because the nature and size of these matters are not indicative of our ongoing business operations.

No definition available.

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No definition available.

Name:	ci_SpecialItemChargeBeforetaxLitigation
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Total pre-tax charges (credits) pursuant to the Tax Cuts and Jobs Act of 2017 classified as a special item, attributable to the parent. Special items are excluded from the calculation of 'adjusted income (loss) from operations' because management believes they are not representative of the underlying results of operations. This is generally because the nature and size of these matters are not indicative of our ongoing business operations.

No definition available.

Name:	ci_SpecialItemChargesPursuantToTaxCutsAndJobsActOf2017
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Total after-tax charges (credits) pursuant to the Tax Cuts and Jobs Act of 2017 classified as a special item, attributable to the parent. Special items are excluded from the calculation of 'adjusted income (loss) from operations' because management believes they are not representative of the underlying results of operations. This is generally because the nature and size of these matters are not indicative of our ongoing business operations.

No definition available.

Name:	ci_SpecialItemChargesPursuantToTaxCutsAndJobsActOf2017AfterTax
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Sum of before-tax tax amounts classified as special items, attributable to the parent. Special items are excluded from the calculation of 'adjusted income (loss) from operations' because management believes they are not representative of the underlying results of operations. This is generally because the nature and size of these matters are not indicative of our ongoing business operations.

No definition available.

Name:	ci_SpecialItemGainOrLossBeforeTaxAttributableToReportngEntity
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Sum of after-tax amounts classified as special items, attributable to the parent. Special items are excluded from the calculation of 'adjusted income (loss) from operations' because management believes they are not representative of the underlying results of operations. This is generally because the nature and size of these matters are not indicative of our ongoing business operations.

No definition available.

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- References

No definition available.

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- References

No definition available.

Name:	ci_SpecialItemsBeforeTaxAbstract
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Before-tax charges (treated as a special item) related to the liquidation of Penn Treaty Network America Insurance Company, together with its subsidiary American Network Insurance Company (collectively 'Penn Treaty', a long-term care insurance carrier), triggering guaranty fund coverage and accrual of a liability. Special items are excluded from the calculation of 'adjusted income (loss) from operations' because management believes they are not representative of the underlying results of operations. This is generally because the nature and size of these matters are not indicative of our ongoing business operations.

No definition available.

Name:	ci_SpecialItemsChargeBeforeTaxPennTreaty
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Amount of income tax expense (benefit) for measurement period adjustment from accounting for tax effect pursuant to Tax Cuts and Jobs Act.

No definition available.

Name:	ci_TaxCutsAndJobsActMeasurementPeriodAdjustmentIncomeTaxExpenseBenefit
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(Decrease) to operating expenses for measurement period adjustment as a result of the Tax Cuts and Jobs Act of 2017 reflecting a decrease in a liability to reimburse a reinsurer for taxes related to a block of business sold through reinsurance.

No definition available.

Name:	ci_TaxCutsAndJobsActOf2017MeasurementPeriodAdjustmentChangeInTaxRateOperatingExpenseBenefit
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
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After-tax impact of decrease to operating expenses for measurement period adjustment resulting from Tax Cuts and Jobs Act of 2017 reflecting a decrease in a liability to reimburse a reinsurer for taxes related to a block of business sold through reinsurance.

No definition available.

Name:	ci_TaxCutsAndJobsActOf2017MeasurementPeriodAdjustmentChangeInTaxRateOperatingExpenseBenefitAfterTax
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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Transaction-related costs primarily consisting of fees for legal, advisory and other professional services, amortization of Bridge Facility fees in 2018, as well as employee costs.

No definition available.

Name:	ci_TransactionRelatedCosts
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Data Type:	xbrli:monetaryItemType
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After-tax transaction-related costs including the impact of tax benefits realized from termination of merger agreement. Transaction-related costs consist primarily of fees for legal, advisory and other professional services as well as employee costs.

No definition available.

Name:	ci_TransactionRelatedCostsAfterTax
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

The difference between the reacquisition price and the net carrying amount of the extinguished debt recognized currently as a component of income in the period of extinguishment, net of tax.

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Data Type:	xbrli:monetaryItemType
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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12317-112629

Reference 2: 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=98514028&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12355-112629