Future policy benefits (Undiscounted & discounted FPB) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Liability for Future Policy Benefit, Activity [Line Items]
Discounted expected future benefit payments	$ 25,526	$ 21,920	$ 20,813	$ 10,775
Term Life Insurance | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	2,492		2,189
Undiscounted expected future gross premiums	2,884		2,503
Discounted expected future benefit payments	1,558	1,427	1,321	921
Discounted expected future gross premiums	1,910		1,682
Whole Life Insurance | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	23,457		15,631
Undiscounted expected future gross premiums	9,478		6,654
Discounted expected future benefit payments	9,928	6,048	5,723	4,785
Discounted expected future gross premiums	7,654		5,173
Accident and Health Insurance Product Line [Member] | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	23,168		23,873
Undiscounted expected future gross premiums	34,055		34,659
Discounted expected future benefit payments	13,319	14,206	13,644	4,939
Discounted expected future gross premiums	20,604		20,193
Insurance, Other | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	977		265
Undiscounted expected future gross premiums	103		102
Discounted expected future benefit payments	721	$ 239	125	$ 130
Discounted expected future gross premiums	$ 92		$ 92