Insurance and Contractholder Liabilities - Future Policy Benefits - Present Values of Expected Premiums and Benefits (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Cigna Healthcare
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	$ 9,233	$ 8,557
Reversal of effect of beginning of period discount rate assumptions	1,154	1,537
Effect of assumption changes and actual variances from expected experience			$ 3	$ 314
Issuances and lapses	1,392	822
Net premiums collected	(1,065)	(1,019)
Interest and other	680	58
Ending balance at original discount rate	11,397	10,269
Effect of end of period discount rate assumptions	(865)	(1,681)
Ending balance	10,532	8,588	9,233	8,557
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	9,633	8,945
Reversal of effect of discount rate assumptions	1,220	1,611
Effect of assumption changes and actual variances from expected experience (2)			203	112
Issuances and lapses	1,316	902
Benefit payments	(1,096)	(1,017)
Interest and other	580	184
Ending balance at original discount rate	11,856	10,737
Effect of discount rate assumptions	(926)	(1,765)
Ending balance	10,930	8,972	9,633	8,945
Liability for future policy benefits	398	384
Other	201	206
Total liability for future policy benefits		590
Total liability for future policy benefits, including assets held for sale	599
Effect of actual variances from expectations	(43)	(12)
Undiscounted expected future gross premiums	20,700	18,500
Discounted expected future gross premiums	14,400	12,500
Undiscounted expected future policy benefits	15,600	13,100
Future policy benefits reserve, reinsurance recoverables	73	154
Cigna Healthcare | Held-for-Sale | Medicare Advantage and related Cigna Healthcare businesses
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Future policy benefits classified as liabilities of business held for sale	422		429
Future policy benefits reserve, reinsurance recoverables reported in assets of businesses held for sale	78
Other Operations
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Total liability for future policy benefits	3,458	3,380	3,538
Undiscounted expected future policy benefits	4,300	4,500
Future policy benefits reserve, reinsurance recoverables	900	1,000
Deferred profit liability included in future policy benefits	400	400
Future policy benefit, excluding deferred profit liability	$ 3,100	$ 3,000	$ 3,200	$ 3,200