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Reinsurance - Reinsurance Recoverables (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) reinsurer	Dec. 31, 2013	Dec. 31, 2023 USD ($)
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	$ 3,926
Allowance for uncollectible reinsurance, including assets held for sale	(30)
Market risk benefits	836		$ 1,081
Total reinsurance recoverables, including assets held for sale	4,732
Held-for-Sale \| Medicare Advantage and related Cigna Healthcare businesses
Ceded Credit Risk [Line Items]
Reinsurance recoverable classified as assets of businesses held for sale	195
Other Current Assets
Ceded Credit Risk [Line Items]
Reinsurance recoverables	159
Fair Value of Collateral Contractually Required to Meet or Exceed Carrying Value of Recoverable
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	620
Collateral provisions exist that may mitigate risk of credit loss
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	2,868
No Collateral
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	438
Ongoing Operations \| A- equivalent and higher current ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	240
Ongoing Operations \| BBB- to BBB+ equivalent current credit ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	63
Ongoing Operations \| Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	148
Ongoing Operations \| Fair Value of Collateral Contractually Required to Meet or Exceed Carrying Value of Recoverable \| A- equivalent and higher current ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	0
Ongoing Operations \| Fair Value of Collateral Contractually Required to Meet or Exceed Carrying Value of Recoverable \| BBB- to BBB+ equivalent current credit ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	0
Ongoing Operations \| Fair Value of Collateral Contractually Required to Meet or Exceed Carrying Value of Recoverable \| Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	144
Ongoing Operations \| Collateral provisions exist that may mitigate risk of credit loss \| A- equivalent and higher current ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	7
Ongoing Operations \| Collateral provisions exist that may mitigate risk of credit loss \| BBB- to BBB+ equivalent current credit ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	0
Ongoing Operations \| Collateral provisions exist that may mitigate risk of credit loss \| Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	1
Ongoing Operations \| No Collateral \| A- equivalent and higher current ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	233
Ongoing Operations \| No Collateral \| BBB- to BBB+ equivalent current credit ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	63
Ongoing Operations \| No Collateral \| Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	3
Acquisition, disposition or run-off activities \| BBB+ equivalent and higher current ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	$ 3,466
Number of reinsurers \| reinsurer	21
Acquisition, disposition or run-off activities \| BBB+ equivalent and higher current ratings \| The Lincoln National Life Insurance Company And Lincoln Life And Annuity Of New York \| Reinsurer Concentration Risk \| Reinsurance Recoverables, Gross, Before Reclassification To Disposal Group Assets Held For Sale, Acquisition Disposition Runoff, Nationally Recognized Statistical Rating Organizations, BBB+ Or Higher
Ceded Credit Risk [Line Items]
Concentration percentage	73.00%
Acquisition, disposition or run-off activities \| Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	$ 9
Acquisition, disposition or run-off activities \| Fair Value of Collateral Contractually Required to Meet or Exceed Carrying Value of Recoverable \| BBB+ equivalent and higher current ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	476
Acquisition, disposition or run-off activities \| Fair Value of Collateral Contractually Required to Meet or Exceed Carrying Value of Recoverable \| Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	0
Acquisition, disposition or run-off activities \| Collateral provisions exist that may mitigate risk of credit loss \| BBB+ equivalent and higher current ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	2,854
Acquisition, disposition or run-off activities \| Collateral provisions exist that may mitigate risk of credit loss \| Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	6
Acquisition, disposition or run-off activities \| No Collateral \| BBB+ equivalent and higher current ratings
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	136
Acquisition, disposition or run-off activities \| No Collateral \| Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables before market risk benefits, including assets held for sale	3
Variable Annuity \| Berkshire
Ceded Credit Risk [Line Items]
Reinsurance, Reinsured Risk, Percentage		100.00%
Remaining overall limit under reinsurance agreement	$ 3,000
Variable Annuity \| Secured \| Berkshire \| Collateralization risk \| Market risk benefits reinsurance recoverable, including IBNR and outstanding claims, less premiums due
Ceded Credit Risk [Line Items]
Concentration percentage	95.00%