Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Operations) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	$ 7,573	$ 4,709	$ 21,207	$ 13,569
Net premiums earned	7,688	4,719	21,690	13,006
Net investment income	739	549	2,121	1,662
Equity in earnings of subsidiaries	0	0	0	0
Net realized gains including OTTI	100	(397)	(510)	(360)
Losses and loss expenses	4,269	2,643	12,197	7,182
Policy benefits	155	89	427	384
Policy acquisition costs and administrative expenses	2,286	1,339	6,860	3,905
Interest (income) expense	152	68	451	207
Other (income) expense	(91)	12	(92)	(61)
Amortization of purchased intangibles	4	51	16	136
Chubb integration expenses	115	9	361	9
Income tax expense	277	132	556	395
Net income	1,360	528	2,525	2,151
Comprehensive income (loss)	1,376	(271)	4,457	768
Chubb Limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	0	0	0	0
Net premiums earned	0	0	0	0
Net investment income	1	1	3	2
Equity in earnings of subsidiaries	1,292	488	2,331	2,037
Net realized gains including OTTI	0	0	(1)	0
Losses and loss expenses	0	0	0	0
Policy benefits	0	0	0	0
Policy acquisition costs and administrative expenses	15	15	48	47
Interest (income) expense	(93)	(8)	(266)	(23)
Other (income) expense	(7)	(51)	(20)	(149)
Amortization of purchased intangibles	0	0	0	0
Chubb integration expenses	12	1	29	1
Income tax expense	6	4	17	12
Net income	1,360	528	2,525	2,151
Comprehensive income (loss)	1,376	(271)	4,457	768
Chubb INA Holdings Inc (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	0	0	0	0
Net premiums earned	0	0	0	0
Net investment income	2	1	9	2
Equity in earnings of subsidiaries	748	255	1,803	755
Net realized gains including OTTI	(2)	(4)	(3)	(6)
Losses and loss expenses	0	0	0	0
Policy benefits	0	0	0	0
Policy acquisition costs and administrative expenses	12	7	144	20
Interest (income) expense	233	68	681	206
Other (income) expense	6	(5)	26	(12)
Amortization of purchased intangibles	0	0	0	0
Chubb integration expenses	16	8	56	8
Income tax expense	(136)	(31)	(323)	(84)
Net income	617	205	1,225	613
Comprehensive income (loss)	627	(265)	2,687	(332)
Other Chubb Limited Subsidiaries
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	7,573	4,709	21,207	13,569
Net premiums earned	7,688	4,719	21,690	13,006
Net investment income	736	547	2,109	1,658
Equity in earnings of subsidiaries	0	0	0	0
Net realized gains including OTTI	102	(393)	(506)	(354)
Losses and loss expenses	4,269	2,643	12,197	7,182
Policy benefits	155	89	427	384
Policy acquisition costs and administrative expenses	2,259	1,317	6,668	3,838
Interest (income) expense	12	8	36	24
Other (income) expense	(90)	68	(98)	100
Amortization of purchased intangibles	4	51	16	136
Chubb integration expenses	87		276	0
Income tax expense	407	159	862	467
Net income	1,423	538	2,909	2,179
Comprehensive income (loss)	1,439	(262)	4,841	795
Consolidating Adjustments and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	0	0	0	0
Net premiums earned	0	0	0	0
Net investment income	0	0	0	0
Equity in earnings of subsidiaries	(2,040)	(743)	(4,134)	(2,792)
Net realized gains including OTTI	0	0	0	0
Losses and loss expenses	0	0	0	0
Policy benefits	0	0	0	0
Policy acquisition costs and administrative expenses	0	0	0	0
Interest (income) expense	0	0	0	0
Other (income) expense	0	0	0	0
Amortization of purchased intangibles	0	0	0	0
Chubb integration expenses	0		0	0
Income tax expense	0	0	0	0
Net income	(2,040)	(743)	(4,134)	(2,792)
Comprehensive income (loss)	$ (2,066)	$ 527	$ (7,528)	$ (463)