Future policy benefits (Undiscounted & discounted FPB) (Details) - Life Insurance [Member] - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Discounted expected future benefit payments	$ 30,635	$ 27,462	$ 23,324
Term Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	4,141	4,073
Undiscounted expected future gross premiums	6,508	7,075
Discounted expected future benefit payments	2,238	2,254	2,321
Discounted expected future gross premiums	4,400	4,703
Whole Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	28,263	23,990
Undiscounted expected future gross premiums	10,346	9,469
Discounted expected future benefit payments	12,057	10,063	5,696
Discounted expected future gross premiums	8,452	7,658
Accident and Health [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	26,584	25,118
Undiscounted expected future gross premiums	38,826	36,869
Discounted expected future benefit payments	15,693	14,650	15,038
Discounted expected future gross premiums	23,133	22,150
Insurance, Other [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	1,126	862
Undiscounted expected future gross premiums	242	115
Discounted expected future benefit payments	647	495	$ 269
Discounted expected future gross premiums	$ 216	$ 103