Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Operations) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Condensed Statement of Income Captions [Line Items]
Net premiums written	$ 7,581	$ 7,639	$ 14,291	$ 13,634
Net premiums earned	7,237	7,405	14,009	14,002
Net investment income	770	708	1,515	1,382
Equity in earnings of subsidiaries	0	0	0	0
Net realized gains (losses) including OTTI	101	(216)	94	(610)
Losses and loss expenses	4,146	4,254	7,935	7,928
Policy benefits	163	146	331	272
Policy acquisition costs and administrative expenses	2,155	2,389	4,228	4,574
Interest (income) expense	147	153	301	299
Other (income) expense	(145)	(29)	(215)	(1)
Amortization of purchased intangibles	65	5	129	12
Chubb integration expenses	72	98	183	246
Income tax expense	200	155	328	279
Net income	1,305	726	2,398	1,165
Comprehensive income (loss)	1,675	1,540	3,082	3,081
Consolidating Adjustments and Eliminations
Condensed Statement of Income Captions [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	(1,918)	(1,213)	(3,646)	(2,094)
Net realized gains (losses) 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	(1,918)	(1,213)	(3,646)	(2,094)
Comprehensive income (loss)	(2,676)	(2,685)	(5,005)	(5,462)
Chubb Limited (Parent Guarantor)
Condensed Statement of Income Captions [Line Items]
Net premiums written	0	0	0	0
Net premiums earned	0	0	0	0
Net investment income	2	1	2	2
Equity in earnings of subsidiaries	1,253	664	2,280	1,039
Net realized gains (losses) including OTTI	(2)	(1)	(2)	(1)
Losses and loss expenses	0	0	0	0
Policy benefits	0	0	0	0
Policy acquisition costs and administrative expenses	18	16	36	33
Interest (income) expense	(84)	(93)	(168)	(173)
Other (income) expense	4	(4)	(2)	(13)
Amortization of purchased intangibles	0	0	0	0
Chubb integration expenses	6	14	6	17
Income tax expense	4	5	10	11
Net income	1,305	726	2,398	1,165
Comprehensive income (loss)	1,675	1,540	3,082	3,081
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Statement of Income Captions [Line Items]
Net premiums written	0	0	0	0
Net premiums earned	0	0	0	0
Net investment income	4	3	7	7
Equity in earnings of subsidiaries	665	549	1,366	1,055
Net realized gains (losses) including OTTI	(1)	(1)	(14)	(1)
Losses and loss expenses	0	0	0	0
Policy benefits	0	0	0	0
Policy acquisition costs and administrative expenses	(2)	96	12	132
Interest (income) expense	212	233	433	448
Other (income) expense	10	10	25	20
Amortization of purchased intangibles	0	0	0	0
Chubb integration expenses	4	(97)	53	40
Income tax expense	(87)	(37)	(199)	(187)
Net income	531	346	1,035	608
Comprehensive income (loss)	920	1,004	1,711	2,060
Other Chubb Limited Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net premiums written	7,581	7,639	14,291	13,634
Net premiums earned	7,237	7,405	14,009	14,002
Net investment income	764	704	1,506	1,373
Equity in earnings of subsidiaries	0	0	0	0
Net realized gains (losses) including OTTI	104	(214)	110	(608)
Losses and loss expenses	4,146	4,254	7,935	7,928
Policy benefits	163	146	331	272
Policy acquisition costs and administrative expenses	2,139	2,277	4,180	4,409
Interest (income) expense	19	13	36	24
Other (income) expense	(159)	(35)	(238)	(8)
Amortization of purchased intangibles	65	5	129	12
Chubb integration expenses	62	181	124	189
Income tax expense	283	187	517	455
Net income	1,387	867	2,611	1,486
Comprehensive income (loss)	$ 1,756	$ 1,681	$ 3,294	$ 3,402