Information provided in connection with outstanding debt of subsidiaries (Condensed Consolidating Statement Of Operations and Comprehensive Income) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written									$ 28,145	$ 17,713	$ 17,799
Net premiums earned	$ 7,059	$ 7,688	$ 7,405	$ 6,597	$ 4,207	$ 4,719	$ 4,360	$ 3,927	28,749	17,213	17,426
Net Investment Income	744	739	708	674	532	549	562	551	2,865	2,194	2,252
Net realized gains (losses) including OTTI	365	100	(216)	(394)	(60)	(397)	126	(89)	(145)	(420)	(507)
Losses and loss expenses	3,855	4,269	4,254	3,674	2,302	2,643	2,417	2,122	16,052	9,484	9,649
Policy benefits	161	155	146	126	159	89	153	142	588	543	517
Policy acquisition costs and administrative expenses									8,985	5,211	5,320
Interest (income) expense									605	300	280
Other (Income) Expense									(222)	(51)	(190)
Amortization of Purchased Intangibles									19	171	108
Chubb integration expenses									492	33	0
Income tax expense									815	462	634
Net income	$ 1,610	$ 1,360	$ 726	$ 439	$ 683	$ 528	$ 942	$ 681	4,135	2,834	2,853
Comprehensive income									4,556	908	2,892
Chubb limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written											0
Net premiums earned											0
Net Investment Income									3	3	2
Equity in earnings of subsidiaries									3,901	2,673	2,707
Net realized gains (losses) including OTTI									0	0	0
Losses and loss expenses											0
Policy benefits											0
Policy acquisition costs and administrative expenses									64	63	78
Interest (income) expense									(353)	(32)	(35)
Other (Income) Expense									(25)	(208)	(201)
Amortization of Purchased Intangibles									0	0	0
Chubb integration expenses									62	3
Income tax expense									21	16	14
Net income									4,135	2,834	2,853
Comprehensive income									4,556	908	2,892
Chubb INA Holdings Inc. (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written									0	0	0
Net premiums earned									0	0	0
Net Investment Income									11	4	2
Equity in earnings of subsidiaries									2,555	1,038	791
Net realized gains (losses) including OTTI									3	(9)	53
Losses and loss expenses									0	0	0
Policy benefits									0	0	0
Policy acquisition costs and administrative expenses									82	28	26
Interest (income) expense									908	302	277
Other (Income) Expense									35	(4)	27
Amortization of Purchased Intangibles									0	0	0
Chubb integration expenses									126	29
Income tax expense									(416)	(349)	(94)
Net income									1,834	1,027	610
Comprehensive income									2,001	(192)	583
Other Chubb Limited Subsidiaries and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written									28,145	17,713	17,799
Net premiums earned									28,749	17,213	17,426
Net Investment Income									2,851	2,187	2,248
Equity in earnings of subsidiaries											0
Net realized gains (losses) including OTTI									(148)	(411)	(560)
Losses and loss expenses									16,052	9,484	9,649
Policy benefits									588	543	517
Policy acquisition costs and administrative expenses									8,839	5,120	5,216
Interest (income) expense									50	30	38
Other (Income) Expense									(232)	161	(16)
Amortization of Purchased Intangibles									19	171	108
Chubb integration expenses									304	1
Income tax expense									1,210	795	714
Net income									4,622	2,684	2,888
Comprehensive income									5,045	757	2,926
Consolidating Adjustments
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written											0
Net premiums earned											0
Equity in earnings of subsidiaries									(6,456)	(3,711)	(3,498)
Net realized gains (losses) including OTTI									0	0	0
Losses and loss expenses											0
Policy benefits											0
Policy acquisition costs and administrative expenses											0
Interest (income) expense											0
Amortization of Purchased Intangibles									0	0	0
Chubb integration expenses									0	0
Income tax expense										0	0
Net income									(6,456)	(3,711)	(3,498)
Comprehensive income									$ (7,046)	$ (565)	$ (3,509)