Unpaid losses and loss expenses Unpaid Losses and loss expenses, claims development (Cumulative Net incurred Loss and Allocated Loss Adjustment Expense) (Details) $ in Millions	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	$ 56,389
North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	12,296
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	5,221
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	9,962
North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	37,676
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	19,547
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	20,014
North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	5,965
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	3,765
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	2,530
North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	21,527
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	18,274
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	3,253
North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	26,806
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	23,607
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	3,225
Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	13,549
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	6,767
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	7,287
Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	20,208
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	17,129
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	3,206
Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	2,679
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,776
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	1,208
Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	2,480
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	2,003
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	494
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	968	$ 989	$ 1,014	$ 1,037	$ 1,073	$ 1,086	$ 1,127	$ 1,122	$ 1,108	$ 1,109
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	219
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 664	650	633	616	587	553	506	422	286	107
Cumulative Number of Reported Claims	43,000
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,997	2,950	2,958	3,115	3,208	3,422	3,524	3,534	3,534	3,540
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	247
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,609	2,520	2,460	2,369	2,228	2,003	1,593	1,189	546	129
Cumulative Number of Reported Claims	25,000
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 458	459	457	461	461	468	514	521	530	525
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	8
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 441	438	425	418	410	384	348	270	196	68
Cumulative Number of Reported Claims	17,000
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,340	1,336	1,337	1,330	1,333	1,333	1,352	1,330	1,417	1,427
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	3
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,338	1,329	1,328	1,326	1,318	1,304	1,278	1,231	1,132	647
Cumulative Number of Reported Claims	455,000
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,933	1,936	1,935	1,932	1,924	1,912	1,888	1,884	1,876	1,848
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	18
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,910	1,904	1,906	1,884	1,873	1,831	1,775	1,676	1,494	1,036
Cumulative Number of Reported Claims	132,000
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,094	1,074	1,054	1,084	1,139	1,172	1,217	1,174	1,181	1,186
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	65
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 913	896	875	826	763	667	532	393	246	78
Cumulative Number of Reported Claims	37,000
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,481	1,483	1,492	1,501	1,513	1,540	1,545	1,590	1,651	1,656
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	12
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,458	1,458	1,461	1,458	1,451	1,433	1,399	1,369	1,186	643
Cumulative Number of Reported Claims	560,000
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 302	305	307	313	320	327	326	326	323	317
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	6
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	279	275	269	266	258	240	221	185	142	64
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	134	134	135	136	136	139	137	143	154	157
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	0
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	134	134	134	133	132	130	127	118	100	$ 45
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	1,007	1,037	1,073	1,100	1,163	1,215	1,217	1,201	1,207
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	264
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 634	617	599	566	532	484	410	295	113
Cumulative Number of Reported Claims	45,000
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,142	3,192	3,340	3,463	3,648	3,710	3,667	3,578	3,528
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	278
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,753	2,669	2,580	2,439	2,199	1,801	1,248	678	164
Cumulative Number of Reported Claims	24,000
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 526	530	538	537	554	595	580	582	594
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	6
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 513	508	500	472	454	391	317	220	80
Cumulative Number of Reported Claims	17,000
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,544	1,545	1,552	1,544	1,543	1,552	1,573	1,655	1,639
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	2
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,552	1,552	1,547	1,540	1,525	1,499	1,478	1,368	816
Cumulative Number of Reported Claims	483,000
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,133	2,134	2,134	2,140	2,153	2,139	2,185	2,199	2,198
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	9
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,119	2,116	2,109	2,100	2,073	2,028	1,919	1,759	1,306
Cumulative Number of Reported Claims	144,000
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,096	1,092	1,081	1,118	1,197	1,277	1,261	1,253	1,186
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	100
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 886	857	815	754	675	567	440	273	104
Cumulative Number of Reported Claims	38,000
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,661	1,669	1,675	1,682	1,691	1,725	1,737	1,790	1,727
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	5
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,641	1,648	1,641	1,627	1,614	1,585	1,526	1,327	699
Cumulative Number of Reported Claims	534,000
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 325	326	326	343	339	338	335	330	329
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	8
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	297	292	283	273	262	247	216	183	91
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	170	172	173	174	175	177	174	175	159
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	167	166	166	164	162	157	147	125	$ 63
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	1,092	1,128	1,154	1,217	1,279	1,276	1,259	1,282
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	338
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 645	628	606	564	501	418	301	116
Cumulative Number of Reported Claims	50,000
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,569	3,700	3,727	3,934	3,966	3,810	3,701	3,552
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	390
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,921	2,743	2,527	2,287	1,852	1,203	604	138
Cumulative Number of Reported Claims	27,000
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 457	462	454	457	514	500	469	486
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	23
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 423	411	394	370	304	214	137	47
Cumulative Number of Reported Claims	15,000
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,592	1,587	1,585	1,600	1,633	1,645	1,740	1,730
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,582	1,583	1,570	1,567	1,552	1,484	1,339	724
Cumulative Number of Reported Claims	545,000
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,561	2,559	2,562	2,556	2,536	2,553	2,542	2,487
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	12
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,535	2,526	2,501	2,472	2,385	2,264	2,078	1,495
Cumulative Number of Reported Claims	148,000
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,174	1,157	1,172	1,229	1,248	1,226	1,199	1,107
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	131
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 927	895	821	745	631	460	265	79
Cumulative Number of Reported Claims	40,000
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,835	1,836	1,853	1,860	1,876	1,907	1,932	1,815
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	7
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,801	1,798	1,781	1,754	1,732	1,656	1,437	789
Cumulative Number of Reported Claims	557,000
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 306	304	300	304	296	295	285	280
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	11
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	272	263	247	230	215	189	157	89
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	154	154	156	151	158	158	152	144
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	0
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	151	150	148	144	140	130	102	$ 56
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	1,177	1,206	1,269	1,378	1,383	1,361	1,366
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	380
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 653	621	584	529	452	326	122
Cumulative Number of Reported Claims	52,000
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,755	3,764	3,792	3,797	3,684	3,587	3,526
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	589
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,820	2,593	2,331	1,973	1,334	662	171
Cumulative Number of Reported Claims	27,000
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 469	479	480	523	527	501	503
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	27
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 424	398	374	323	246	145	52
Cumulative Number of Reported Claims	16,000
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,820	1,824	1,811	1,775	1,794	1,884	1,904
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	26
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,790	1,779	1,754	1,726	1,650	1,499	844
Cumulative Number of Reported Claims	650,000
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,465	2,457	2,464	2,476	2,538	2,529	2,433
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	17
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,422	2,391	2,364	2,308	2,205	2,046	1,449
Cumulative Number of Reported Claims	154,000
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,263	1,328	1,317	1,327	1,298	1,234	1,138
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	117
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 974	851	760	642	500	303	119
Cumulative Number of Reported Claims	42,000
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,911	1,913	1,883	1,880	1,901	1,914	1,920
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	35
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,845	1,840	1,831	1,807	1,740	1,554	938
Cumulative Number of Reported Claims	566,000
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 243	238	238	229	230	222	218
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	11
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	205	189	172	157	140	111	56
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	181	181	183	187	184	182	176
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	2
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	176	175	172	166	155	129	$ 56
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	1,176	1,376	1,393	1,399	1,380	1,412
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	465
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 601	564	516	437	313	120
Cumulative Number of Reported Claims	50,000
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,434	3,545	3,623	3,573	3,491	3,315
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	758
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,322	2,000	1,698	1,160	616	161
Cumulative Number of Reported Claims	26,000
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 590	604	616	576	565	531
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	36
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 496	446	381	312	175	66
Cumulative Number of Reported Claims	17,000
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,519	2,509	2,517	2,501	2,602	2,699
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	65
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,427	2,403	2,389	2,299	2,083	977
Cumulative Number of Reported Claims	764,000
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,000	2,991	2,991	2,995	3,062	3,027
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	16
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,930	2,863	2,793	2,661	2,514	1,693
Cumulative Number of Reported Claims	163,000
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,319	1,283	1,318	1,271	1,224	1,128
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	149
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 931	805	647	494	296	90
Cumulative Number of Reported Claims	43,000
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,096	2,099	2,075	2,093	2,107	2,067
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	23
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,062	2,004	1,964	1,893	1,726	980
Cumulative Number of Reported Claims	577,000
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 212	213	212	214	210	208
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	4
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	172	152	137	120	98	46
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	456	453	449	451	421	395
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	12
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	433	427	414	400	321	$ 191
Short-duration Insurance Contracts, Accident Year 2018 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	1,384	1,385	1,380	1,361	1,359
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	631
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 597	528	451	329	130
Cumulative Number of Reported Claims	51,000
Short-duration Insurance Contracts, Accident Year 2018 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,900	3,820	3,688	3,485	3,367
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,041
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,335	1,773	1,301	753	189
Cumulative Number of Reported Claims	28,000
Short-duration Insurance Contracts, Accident Year 2018 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 575	579	574	563	535
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	25
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 472	365	270	169	74
Cumulative Number of Reported Claims	17,000
Short-duration Insurance Contracts, Accident Year 2018 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,170	2,161	2,169	2,234	2,047
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	35
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,113	2,068	2,012	1,820	1,025
Cumulative Number of Reported Claims	903,000
Short-duration Insurance Contracts, Accident Year 2018 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,131	3,110	3,095	3,029	3,001
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	93
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,971	2,857	2,699	2,542	1,922
Cumulative Number of Reported Claims	170,000
Short-duration Insurance Contracts, Accident Year 2018 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,330	1,375	1,332	1,273	1,224
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	282
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 718	602	465	309	104
Cumulative Number of Reported Claims	43,000
Short-duration Insurance Contracts, Accident Year 2018 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,013	2,044	2,070	2,107	2,022
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	39
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,893	1,878	1,812	1,620	930
Cumulative Number of Reported Claims	612,000
Short-duration Insurance Contracts, Accident Year 2018 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 246	243	247	240	237
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	12
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	166	145	122	93	40
Short-duration Insurance Contracts, Accident Year 2018 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	291	286	290	287	279
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	7
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	273	269	266	250	$ 94
Short-Duration Insurance Contract, Accident Year 2019 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	1,409	1,400	1,384	1,391
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	656
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 575	467	341	143
Cumulative Number of Reported Claims	48,000
Short-Duration Insurance Contract, Accident Year 2019 [Member] | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 4,050	3,858	3,620	3,445
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,488
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,888	1,245	669	175
Cumulative Number of Reported Claims	30,000
Short-Duration Insurance Contract, Accident Year 2019 [Member] | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 743	685	636	605
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	143
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 465	318	189	70
Cumulative Number of Reported Claims	17,000
Short-Duration Insurance Contract, Accident Year 2019 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,944	1,953	2,031	2,046
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	52
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,856	1,800	1,672	1,028
Cumulative Number of Reported Claims	1,043,000
Short-Duration Insurance Contract, Accident Year 2019 [Member] | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,978	2,986	2,985	2,948
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	116
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,718	2,610	2,431	1,663
Cumulative Number of Reported Claims	156,000
Short-Duration Insurance Contract, Accident Year 2019 [Member] | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,373	1,382	1,360	1,295
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	358
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 642	440	313	116
Cumulative Number of Reported Claims	42,000
Short-Duration Insurance Contract, Accident Year 2019 [Member] | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,989	2,000	2,060	2,044
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	(15)
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,869	1,804	1,620	979
Cumulative Number of Reported Claims	631,000
Short-Duration Insurance Contract, Accident Year 2019 [Member] | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 235	236	240	232
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	37
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	137	114	88	39
Short-Duration Insurance Contract, Accident Year 2019 [Member] | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	121	127	130	132
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	8
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	103	95	81	$ 35
Short-Duration Insurance Contract, Accident Year 2020 | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	1,409	1,388	1,367
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	852
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 390	282	111
Cumulative Number of Reported Claims	31,000
Short-Duration Insurance Contract, Accident Year 2020 | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,919	3,826	4,102
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	2,184
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,147	589	152
Cumulative Number of Reported Claims	24,000
Short-Duration Insurance Contract, Accident Year 2020 | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 656	633	640
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	265
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 273	156	54
Cumulative Number of Reported Claims	11,000
Short-Duration Insurance Contract, Accident Year 2020 | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,726	2,942	3,139
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	105
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,466	2,260	1,390
Cumulative Number of Reported Claims	1,124,000
Short-Duration Insurance Contract, Accident Year 2020 | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,626	2,627	2,922
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	206
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,223	1,990	1,330
Cumulative Number of Reported Claims	123,000
Short-Duration Insurance Contract, Accident Year 2020 | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,509	1,589	1,669
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	835
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 425	271	101
Cumulative Number of Reported Claims	34,000
Short-Duration Insurance Contract, Accident Year 2020 | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,120	2,244	2,378
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	164
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,746	1,602	1,003
Cumulative Number of Reported Claims	533,000
Short-Duration Insurance Contract, Accident Year 2020 | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 236	245	241
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	60
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	123	98	41
Short-Duration Insurance Contract, Accident Year 2020 | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	277	253	209
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	34
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	215	177	$ 62
Short-Duration Insurance Contract, Accident Year 2021 | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	1,330	1,348
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	780
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 331	120
Cumulative Number of Reported Claims	37,000
Short-Duration Insurance Contract, Accident Year 2021 | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 4,349	4,315
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	3,263
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 608	174
Cumulative Number of Reported Claims	24,000
Short-Duration Insurance Contract, Accident Year 2021 | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 709	675
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	379
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 176	60
Cumulative Number of Reported Claims	12,000
Short-Duration Insurance Contract, Accident Year 2021 | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,824	2,941
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	368
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,100	1,085
Cumulative Number of Reported Claims	857,000
Short-Duration Insurance Contract, Accident Year 2021 | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,877	3,027
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	245
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 2,368	1,583
Cumulative Number of Reported Claims	129,000
Short-Duration Insurance Contract, Accident Year 2021 | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,650	1,604
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,111
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 268	110
Cumulative Number of Reported Claims	35,000
Short-Duration Insurance Contract, Accident Year 2021 | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,374	2,462
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	241
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,692	944
Cumulative Number of Reported Claims	541,000
Short-Duration Insurance Contract, Accident Year 2021 | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 281	277
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	136
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	86	35
Short-Duration Insurance Contract, Accident Year 2021 | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	350	340
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	43
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	277	$ 158
Short-Duration Insurance Contract, Accident Year 2022 | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	1,344
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	988
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 131
Cumulative Number of Reported Claims	32,000
Short-Duration Insurance Contract, Accident Year 2022 | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 4,561
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	4,176
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 144
Cumulative Number of Reported Claims	24,000
Short-Duration Insurance Contract, Accident Year 2022 | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 782
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	611
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 82
Cumulative Number of Reported Claims	11,000
Short-Duration Insurance Contract, Accident Year 2022 | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,048
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,467
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,050
Cumulative Number of Reported Claims	751,000
Short-Duration Insurance Contract, Accident Year 2022 | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 3,102
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,217
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,411
Cumulative Number of Reported Claims	94,000
Short-Duration Insurance Contract, Accident Year 2022 | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 1,741
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	1,475
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 83
Cumulative Number of Reported Claims	29,000
Short-Duration Insurance Contract, Accident Year 2022 | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 2,728
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	696
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,122
Cumulative Number of Reported Claims	597,000
Short-Duration Insurance Contract, Accident Year 2022 | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 293
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	206
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	39
Short-Duration Insurance Contract, Accident Year 2022 | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	346
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	220
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	74
Accident years prior to 2013 | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	2,887
Accident years prior to 2013 | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	1,885
Accident years prior to 2013 | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	330
Accident years prior to 2013 | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	0
Accident years prior to 2013 | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	26
Accident years prior to 2013 | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	505
Accident years prior to 2013 | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	127
Accident years prior to 2013 | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	305
Accident years prior to 2013 | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	17
Accident years 2013 - 2022 | North America Commercial P&C Insurance - Workers' Compensation [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	7,075
Accident years 2013 - 2022 | North America Commercial P&C Insurance - Liability [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	18,129
Accident years 2013 - 2022 | North America Commercial P&C Insurance - Other Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	2,200
Accident years 2013 - 2022 | North America Commercial P&C Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	3,253
Accident years 2013 - 2022 | North America Personal P&C Insurance [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	3,199
Accident years 2013 - 2022 | Overseas General Insurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	6,782
Accident years 2013 - 2022 | Overseas General Insurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	3,079
Accident years 2013 - 2022 | Global Reinsurance - Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	903
Accident years 2013 - 2022 | Global Reinsurance - Non-Casualty [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	$ 477