Future policy benefits (Undiscounted & discounted FPB) (Details) - Life Insurance [Member] - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Liability for Future Policy Benefit, Activity [Line Items]
Discounted expected future benefit payments	$ 27,462	$ 23,324	$ 10,387	$ 11,100
Term Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	4,073	3,914	1,163
Undiscounted expected future gross premiums	7,075	6,823	1,334
Discounted expected future benefit payments	2,254	2,321	832	739
Discounted expected future gross premiums	4,703	4,555	1,041
Whole Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	23,990	16,224	9,898
Undiscounted expected future gross premiums	9,469	6,912	3,583
Discounted expected future benefit payments	10,063	5,696	4,493	4,886
Discounted expected future gross premiums	7,658	5,398	2,656
Accident and Health [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	25,118	25,617	6,271
Undiscounted expected future gross premiums	36,869	37,765	9,029
Discounted expected future benefit payments	14,650	15,038	4,935	5,351
Discounted expected future gross premiums	22,150	22,111	6,457
Insurance, Other [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	862	407	114
Undiscounted expected future gross premiums	115	115	45
Discounted expected future benefit payments	495	269	127	$ 124
Discounted expected future gross premiums	$ 103	$ 100	$ 38