Future policy benefits (Undiscounted & discounted FPB) (Details) - Segment Life [Member] - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Discounted expected future benefit payments	$ 31,056	$ 27,462	$ 26,477	$ 23,324
Term Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	4,188		4,043
Undiscounted expected future gross premiums	6,669		6,588
Discounted expected future benefit payments	2,309	2,254	2,586	2,321
Discounted expected future gross premiums	4,504		3,741
Whole Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	28,111		23,454
Undiscounted expected future gross premiums	10,363		9,478
Discounted expected future benefit payments	11,909	10,063	9,606	5,696
Discounted expected future gross premiums	8,404		7,654
Accident and Health Insurance Product Line [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	27,423		23,914
Undiscounted expected future gross premiums	40,183		35,029
Discounted expected future benefit payments	16,219	14,650	13,625	15,038
Discounted expected future gross premiums	23,655		21,241
Insurance, Other
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	1,046		774
Undiscounted expected future gross premiums	200		104
Discounted expected future benefit payments	619	$ 495	660	$ 269
Discounted expected future gross premiums	$ 177		$ 92