Amount by which Company may increase its maximum borrowing capacity under credit agreement.

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Debt Instrument, Repurchased Face Amount, Tender Offer

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Amount by which Company may increase the term length of the credit agreement.

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Gain (Loss) On Extinguishment Of Debt, Net Of Tax

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The debt-to adjusted capital ratio which the Company must not exceed in accordance with the terms of the line of credit facility agreement.

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Number of banks participating in revolving credit and letter of credit agreement

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Payments For Debt Tender And Redemption

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Subsidiary Debt Exchanged For New Debt Issued By Parent

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Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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Face (par) amount of debt instrument at time of issuance.

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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.

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Face (par) amount of the original debt instrument that was repurchased.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Weighted average interest rate of short-term debt outstanding calculated at point in time.

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Debt - Narrative (Details)			1 Months Ended	2 Months Ended	3 Months Ended	12 Months Ended
Debt - Narrative (Details)	Dec. 31, 2020 USD ($) bank	Apr. 01, 2020 USD ($)	Oct. 31, 2020 USD ($) bank	Apr. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) bank	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Mar. 16, 2020 USD ($)
Debt Instrument [Line Items]
Aggregate principal amount of outstanding debt securities under tender offer and optional redemption				$ 3,500,000,000
Aggregate principal amount of outstanding debt securities repurchased under tender offer				1,500,000,000
Aggregate principal amount of outstanding debt securities repurchased under optional redemption				2,000,000,000.0
Loss on repurchase of debt, pre-tax				199,000,000		$ 199,000,000	$ 2,000,000	$ 0
Loss on repurchase of debt, after-tax				$ 151,000,000
Notes issued by Express Scripts, Medco and Old Cigna exchanged for Notes issued by Cigna					$ 12,700,000,000
Repayment of long-term debt						8,047,000,000	4,491,000,000	131,000,000
Payments for debt tender and redemption						3,500,000,000
Commercial paper	$ 1,030,000,000				$ 944,000,000	1,030,000,000	944,000,000
Interest expense on long-term and short-term debt						1,400,000,000	$ 1,600,000,000	$ 507,000,000
Commercial Paper
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 4,250,000,000					$ 4,250,000,000
Average interest rate	0.20%					0.20%
Revolving Credit Agreement
Debt Instrument [Line Items]
Number of participating banks \| bank	23					23
Maximum borrowing capacity	$ 3,250,000,000					$ 3,250,000,000
Amount by which credit facilty amount can be increased	500,000,000					$ 500,000,000
Amount by which credit facilty term length can be increased						1 year
Revolving Credit Agreement \| Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 500,000,000					$ 500,000,000
Revolving Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Leverage ratio covenant	60.00%					60.00%
Outstanding balances	$ 0					$ 0
364-day Revolving Credit Agreement, Maturing October 2021 \| Revolving Credit Facility
Debt Instrument [Line Items]
Number of participating banks \| bank			23
Maximum borrowing capacity			$ 1,000,000,000.0
Credit agreement term			364 days
Leverage ratio covenant	60.00%					60.00%
Outstanding balances	$ 0					$ 0
364-day Revolving Credit Agreement, Maturing October 2020 \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 1,000,000,000.0
Credit agreement term						364 days
Leverage ratio covenant	60.00%					60.00%
Outstanding balances	$ 0					$ 0
364-Day Term Loan \| Line of Credit
Debt Instrument [Line Items]
Aggregate principal amount		$ 1,400,000,000
Credit agreement term		364 days
Repayment of short-term debt	$ 1,400,000,000
Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount									$ 3,500,000,000