Future policy benefits (Undiscounted & discounted FPB) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Liability for Future Policy Benefit, Activity [Line Items]
Discounted expected future benefit payments	$ 22,067	$ 21,920	$ 9,045	$ 10,775
Term Life Insurance | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	2,381		1,266
Undiscounted expected future gross premiums	2,701		1,382
Discounted expected future benefit payments	1,531	1,427	788	921
Discounted expected future gross premiums	1,805		1,045
Whole Life Insurance | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	16,890		9,799
Undiscounted expected future gross premiums	6,971		3,457
Discounted expected future benefit payments	6,678	6,048	3,871	4,785
Discounted expected future gross premiums	5,455		2,499
Accident and Health Insurance Product Line [Member] | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	22,461		5,903
Undiscounted expected future gross premiums	33,371		8,752
Discounted expected future benefit payments	13,603	14,206	4,257	4,939
Discounted expected future gross premiums	20,339		5,683
Insurance, Other | Segment Life [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	374		216
Undiscounted expected future gross premiums	94		72
Discounted expected future benefit payments	255	$ 239	129	$ 130
Discounted expected future gross premiums	$ 84		$ 64