Insurance and Contractholder Liabilities - Unpaid Claims and Claim Expenses - Cigna Healthcare - Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Held-for-Sale | Medicare Advantage and related Cigna Healthcare businesses
Paid costs related to:
Unpaid claims classified as liabilities of business held for sale	$ 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, including reported claims in process	4,800	$ 3,900
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning balance	4,176	4,261	$ 3,695
Less: Reinsurance and other amounts recoverable	221	261	237
Beginning balance, net	3,955	4,000	3,458
Incurred costs related to:
Current year	35,953	31,342	31,755
Prior years	(279)	(259)	(219)
Total incurred	35,674	31,083	31,536
Paid costs related to:
Current year	31,322	27,583	27,929
Prior years	3,451	3,545	3,065
Total paid	34,773	31,128	30,994
Ending balance, net		3,955	4,000
Add: Reinsurance and other amounts recoverable		221	261
Ending balance (1)		$ 4,176	$ 4,261
Ending balance, net, including held for sale liabilities	4,856
Add: Reinsurance, including held for sale liabilities	236
Ending balance, including held for sale liabilities	$ 5,092