Reinsurance (Consolidated Reinsurance) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Premiums written [Abstract]
Direct	$ 52,969	$ 47,511	$ 42,811
Assumed	4,557	4,467	3,928
Ceded	(10,165)	(10,258)	(8,912)
Net	47,361	41,720	37,827
Premiums earned [Abstract]
Direct	51,582	46,160	41,116
Assumed	4,289	4,395	3,609
Ceded	(10,159)	(10,195)	(8,433)
Net premiums earned	45,712	40,360	36,292
Policyholder Benefits and Claims Incurred, Ceded	$ 7,200	$ 6,900	$ 5,900