Future policy benefits (Undiscounted & discounted FPB) (Details) - Segment Life [Member] - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Liability for Future Policy Benefit, Activity [Line Items]
Discounted expected future benefit payments	$ 33,289	$ 32,775	$ 31,484	$ 30,635
Term Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	4,636		4,266
Undiscounted expected future gross premiums	6,838		6,595
Discounted expected future benefit payments	2,331	2,313	2,268	2,238
Discounted expected future gross premiums	4,609		4,460
Whole Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	33,780		29,099
Undiscounted expected future gross premiums	11,052		10,390
Discounted expected future benefit payments	14,167	13,791	12,429	12,057
Discounted expected future gross premiums	9,213		8,518
Accident and Health Insurance Product Line [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	26,758		26,695
Undiscounted expected future gross premiums	39,618		39,108
Discounted expected future benefit payments	15,471	15,587	15,930	15,693
Discounted expected future gross premiums	23,867		23,346
Insurance, Other
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	2,530		1,556
Undiscounted expected future gross premiums	851		478
Discounted expected future benefit payments	1,320	$ 1,084	857	$ 647
Discounted expected future gross premiums	$ 798		$ 437