Insurance Liabilities - Expected future benefits, expenses, and gross premiums (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
General Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefits and expense	$ 3,194	$ 3,325	$ 3,677
Undiscounted expected future gross premiums	4,403	4,558	4,899
Discounted expected future gross premiums (at current discount rate)	3,000
Individual Retirement
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefits and expense	2,131	1,959	1,747
Undiscounted expected future gross premiums	0	0	0
Group Retirement
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefits and expense	313	321	328
Undiscounted expected future gross premiums	0	0	0
Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefits and expense	40,489	38,909	38,869
Undiscounted expected future gross premiums	30,458	29,035	29,272
Discounted expected future gross premiums (at current discount rate)	20,200
Institutional Markets
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefits and expense	38,253	25,066	20,839
Undiscounted expected future gross premiums	0	0	0
Other Operations
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefits and expense	43,071	44,530	46,038
Undiscounted expected future gross premiums	2,146	$ 2,262	$ 2,437
Discounted expected future gross premiums (at current discount rate)	$ 1,400