Segment Information (Operations By Segment) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net premiums written	$ 47,361	$ 41,720	$ 37,827
Net premiums earned	45,712	40,360	36,292
Losses and loss expenses	24,100	22,572	21,030
Policy benefits	3,628	2,314	1,740
Policy acquisition costs	8,259	7,339	6,758
Administrative expenses	4,007	3,395	3,135
Underwriting Income (Loss)	5,718	4,740	3,629
Net investment income	4,937	3,742	3,456
Other (income) expense	(836)	89	(2,367)
Amortization of purchased intangibles	310	285	287
Segment income (loss)	11,181	8,108	9,165
Net realized gains (losses)	(607)	(1,085)	1,030
Market risk benefits gains (losses)	(307)	80	91
Interest expense	672	570	492
Cigna integration expenses	69	48	0
Income tax expense	511	1,239	1,269
Net income	9,015	5,246	8,525
Net loss attributable to noncontrolling interests	(13)	0	0
Net income attributable to Chubb	9,028	5,246	8,525
North America Commercial P&C Insurance [Member]
Segment Reporting Information [Line Items]
Net premiums written	19,237	17,889	16,415
Net premiums earned	18,416	17,107	15,461
Losses and loss expenses	11,256	10,828	10,015
Policy benefits	0	0	0
Policy acquisition costs	2,515	2,313	2,082
Administrative expenses	1,250	1,113	1,052
Underwriting Income (Loss)	3,395	2,853	2,312
Net investment income	3,017	2,247	2,078
Other (income) expense	22	17	31
Amortization of purchased intangibles	0	0	0
Segment income (loss)	6,390	5,083	4,359
North America Personal P&C Insurance [Member]
Segment Reporting Information [Line Items]
Net premiums written	5,878	5,313	5,002
Net premiums earned	5,536	5,180	4,915
Losses and loss expenses	3,511	3,186	2,924
Policy benefits	0	0	0
Policy acquisition costs	1,128	1,057	1,001
Administrative expenses	329	291	276
Underwriting Income (Loss)	568	646	714
Net investment income	358	283	249
Other (income) expense	3	4	(2)
Amortization of purchased intangibles	9	10	10
Segment income (loss)	914	915	955
North America Agricultural Insurance [Member]
Segment Reporting Information [Line Items]
Net premiums written	3,188	2,907	2,388
Net premiums earned	3,169	2,838	2,338
Losses and loss expenses	2,874	2,557	1,962
Policy benefits	0	0	0
Policy acquisition costs	150	126	124
Administrative expenses	(1)	(10)	(3)
Underwriting Income (Loss)	146	165	255
Net investment income	63	36	28
Other (income) expense	1	1	1
Amortization of purchased intangibles	25	26	26
Segment income (loss)	183	174	256
Overseas General Insurance [Member]
Segment Reporting Information [Line Items]
Net premiums written	12,575	11,060	10,713
Net premiums earned	12,231	10,803	10,441
Losses and loss expenses	5,643	4,894	4,783
Policy benefits	457	358	360
Policy acquisition costs	3,113	2,818	2,799
Administrative expenses	1,219	1,070	1,078
Underwriting Income (Loss)	1,799	1,663	1,421
Net investment income	895	626	597
Other (income) expense	(25)	2	0
Amortization of purchased intangibles	70	57	48
Segment income (loss)	2,649	2,230	1,970
Global Reinsurance [Member]
Segment Reporting Information [Line Items]
Net premiums written	1,018	943	873
Net premiums earned	962	922	798
Losses and loss expenses	426	670	632
Policy benefits	0	0	0
Policy acquisition costs	264	240	200
Administrative expenses	37	36	35
Underwriting Income (Loss)	235	(24)	(69)
Net investment income	208	281	331
Other (income) expense	(2)	1	0
Amortization of purchased intangibles	0	0	0
Segment income (loss)	445	256	262
Life Insurance [Member]
Segment Reporting Information [Line Items]
Net premiums written	5,465	3,608	2,436
Net premiums earned	5,398	3,510	2,339
Losses and loss expenses	114	85	150
Policy benefits	3,216	1,998	1,388
Policy acquisition costs	1,089	785	552
Administrative expenses	771	510	332
Underwriting Income (Loss)	208	132	(83)
Net investment income	756	509	407
Other (income) expense	(115)	(30)	(108)
Amortization of purchased intangibles	30	10	5
Segment income (loss)	1,049	661	427
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Net premiums written	0	0	0
Net premiums earned	0	0	0
Losses and loss expenses	281	363	572
Policy benefits	0	0	0
Policy acquisition costs	0	0	0
Administrative expenses	402	385	365
Underwriting Income (Loss)	(683)	(748)	(937)
Net investment income	25	0	(55)
Other (income) expense	(380)	292	(2,118)
Amortization of purchased intangibles	176	182	198
Segment income (loss)	(454)	(1,222)	928
Net realized gains (losses)	(602)	(1,074)	1,038
Market risk benefits gains (losses)	(307)	80	91
Interest expense	672	570	492
Cigna integration expenses	69	48
Income tax expense	511	1,239	1,269
Net income	(2,615)	(4,073)	296
Net loss attributable to noncontrolling interests	(13)
Net income attributable to Chubb	(2,602)
Segment Measure Reconciling Items [Member]
Segment Reporting Information [Line Items]
Net premiums written	0	0	0
Net premiums earned	0	0	0
Losses and loss expenses	(5)	(11)	(8)
Policy benefits	(45)	(42)	(8)
Policy acquisition costs	0	0	0
Administrative expenses	0	0	0
Underwriting Income (Loss)	50	53	16
Net investment income	(385)	(240)	(179)
Other (income) expense	(340)	(198)	(171)
Amortization of purchased intangibles	0	0	0
Segment income (loss)	5	11	8
Net realized gains (losses)	(5)	(11)	(8)
Market risk benefits gains (losses)	0	0	0
Interest expense	0	0	0
Cigna integration expenses	0	0
Income tax expense	0	0	0
Net income	0	$ 0	$ 0
Net loss attributable to noncontrolling interests	0
Net income attributable to Chubb	$ 0