Insurance and Contractholder Liabilities - Unpaid Claims and Claim Expenses - Cigna Healthcare - Activity (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Held-for-Sale | Medicare Advantage and related Cigna Healthcare businesses
Paid costs related to:
Unpaid claims classified as liabilities of business held for sale	$ 937		$ 823
Cigna Healthcare
Liability for Claims and Claims Adjustment Expense [Line Items]
Total of incurred but not reported liabilities plus expected claim development on reported claims and reported claims in process	4,700	$ 5,000
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning balance		4,176
Less: Reinsurance and other amounts recoverable		221
Beginning balance, net		3,955
Beginning balance, including held for sale liabilities	5,092
Less: Reinsurance, including held for sale liabilities	236
Beginning balance, net, including held for sale liabilities	4,856
Incurred costs related to:
Current year	28,314	26,788
Prior years	(422)	(237)
Total incurred	27,892	26,551
Paid costs related to:
Current year	23,761	22,053
Prior years	4,059	3,362
Total paid	27,820	25,415
Ending balance, net		5,091
Add: Reinsurance and other amounts recoverable		226
Ending balance		$ 5,317
Ending balance, net, including held for sale liabilities	4,928
Add: Reinsurance, including held for sale liabilities	160
Ending balance, including held for sale liabilities	$ 5,088