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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	$ 7,639	$ 4,784	$ 13,634	$ 8,860
Net premiums earned	7,405	4,360	14,002	8,287
Net investment income	708	562	1,382	1,113
Equity in earnings of subsidiaries	0	0	0	0
Net realized gains (losses) including OTTI	(216)	126	(610)	37
Losses and loss expenses	4,254	2,417	7,928	4,539
Policy benefits	146	153	272	295
Policy acquisition costs and administrative expenses	2,389	1,305	4,574	2,566
Interest (income) expense	153	71	299	139
Other (income) expense	(29)	(38)	(1)	(73)
Amortization of purchased intangibles	5	55	12	85
Chubb integration expenses	98	0	246	0
Income tax expense	155	143	279	263
Net income (loss)	726	942	1,165	1,623
Comprehensive income (loss)	1,540	397	3,081	1,039
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	0	2	1
Equity in earnings of subsidiaries	664	901	1,039	1,549
Net realized gains (losses) including OTTI	(1)	0	(1)	0
Losses and loss expenses	0	0	0	0
Policy benefits	0	0	0	0
Policy acquisition costs and administrative expenses	16	18	33	32
Interest (income) expense	(93)	(7)	(173)	(15)
Other (income) expense	(4)	(57)	(13)	(98)
Amortization of purchased intangibles	0	0	0	0
Chubb integration expenses	14		17
Income tax expense	5	5	11	8
Net income (loss)	726	942	1,165	1,623
Comprehensive income (loss)	1,540	397	3,081	1,039
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	3	0	7	1
Equity in earnings of subsidiaries	549	296	1,055	500
Net realized gains (losses) including OTTI	(1)	(2)	(1)	(2)
Losses and loss expenses	0	0	0	0
Policy benefits	0	0	0	0
Policy acquisition costs and administrative expenses	96	7	132	13
Interest (income) expense	233	69	448	138
Other (income) expense	10	(4)	20	(7)
Amortization of purchased intangibles	0	0	0	0
Chubb integration expenses	(97)		40
Income tax expense	(37)	(27)	(187)	(53)
Net income (loss)	346	249	608	408
Comprehensive income (loss)	1,004	(91)	2,060	(67)
Other Chubb Limited Subsidiaries
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	7,639	4,784	13,634	8,860
Net premiums earned	7,405	4,360	14,002	8,287
Net investment income	704	562	1,373	1,111
Equity in earnings of subsidiaries	0	0	0	0
Net realized gains (losses) including OTTI	(214)	128	(608)	39
Losses and loss expenses	4,254	2,417	7,928	4,539
Policy benefits	146	153	272	295
Policy acquisition costs and administrative expenses	2,277	1,280	4,409	2,521
Interest (income) expense	13	9	24	16
Other (income) expense	(35)	23	(8)	32
Amortization of purchased intangibles	5	55	12	85
Chubb integration expenses	181		189
Income tax expense	187	165	455	308
Net income (loss)	867	948	1,486	1,641
Comprehensive income (loss)	1,681	403	3,402	1,057
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	(1,213)	(1,197)	(2,094)	(2,049)
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
Income tax expense	0	0	0	0
Net income (loss)	(1,213)	(1,197)	(2,094)	(2,049)
Comprehensive income (loss)	$ (2,685)	$ (312)	$ (5,462)	$ (990)