Schedule IV (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Premiums	$ 33,254	$ 31,856	$ 31,285
Reportable Segments
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct	35,487	36,792	34,883
Ceded Premiums Earned	13,394	13,391	12,503
Assumed	11,161	8,455	8,905
Premiums	$ 33,254	$ 31,856	$ 31,285
Percent of Amount Assumed to Net	33.60%	26.50%	28.50%
Reportable Segments | General Insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct	$ 30,781	$ 32,053	$ 30,279
Ceded Premiums Earned	12,268	12,425	11,301
Assumed	7,050	7,137	6,640
Premiums	$ 25,563	$ 26,765	$ 25,618
Percent of Amount Assumed to Net	27.60%	26.70%	25.90%
Reportable Segments | Life and Retirement
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct	$ 4,706	$ 4,739	$ 4,604
Ceded Premiums Earned	1,126	966	1,202
Assumed	4,111	1,318	2,265
Premiums	$ 7,691	$ 5,091	$ 5,667
Percent of Amount Assumed to Net	53.50%	25.90%	40.00%
Long Duration Insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct	$ 1,308,474	$ 1,280,831	$ 1,280,090
Ceded Premiums Earned	363,471	346,879	363,008
Assumed	173	188	192
Premiums	$ 945,176	$ 934,140	$ 917,274
Percent of Amount Assumed to Net	0.00%	0.00%	0.00%