Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Operations) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Statement of Income Captions [Line Items]
Net premiums written	$ 6,710	$ 5,995
Net premiums earned	6,772	6,597
Net investment income	745	674
Equity in earnings of subsidiaries	0	0
Net realized gains (losses) including OTTI	(7)	(394)
Losses and loss expenses	3,789	3,674
Policy benefits	168	126
Policy acquisition costs and administrative expenses	2,073	2,185
Interest (income) expense	154	146
Other (income) expense	(70)	28
Amortization of purchased intangibles	64	7
Chubb integration expenses	111	148
Income tax expense	128	124
Net income	1,093	439
Comprehensive income (loss)	1,407	1,541
Consolidating Adjustments and Eliminations
Condensed Statement of Income Captions [Line Items]
Net premiums written	0	0
Net premiums earned	0	0
Net investment income	0	0
Equity in earnings of subsidiaries	(1,728)	(881)
Net realized gains (losses) including OTTI	0	0
Losses and loss expenses	0	0
Policy benefits	0	0
Policy acquisition costs and administrative expenses	0	0
Interest (income) expense	0	0
Other (income) expense	0	0
Amortization of purchased intangibles	0	0
Chubb integration expenses	0	0
Income tax expense	0	0
Net income	(1,728)	(881)
Comprehensive income (loss)	(2,329)	(2,777)
Chubb Limited (Parent Guarantor)
Condensed Statement of Income Captions [Line Items]
Net premiums written	0	0
Net premiums earned	0	0
Net investment income	0	1
Equity in earnings of subsidiaries	1,027	375
Net realized gains (losses) including OTTI	0	0
Losses and loss expenses	0	0
Policy benefits	0	0
Policy acquisition costs and administrative expenses	18	17
Interest (income) expense	(84)	(80)
Other (income) expense	(6)	(9)
Amortization of purchased intangibles	0	0
Chubb integration expenses	0	3
Income tax expense	6	6
Net income	1,093	439
Comprehensive income (loss)	1,407	1,541
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Statement of Income Captions [Line Items]
Net premiums written	0	0
Net premiums earned	0	0
Net investment income	3	4
Equity in earnings of subsidiaries	701	506
Net realized gains (losses) including OTTI	(13)	0
Losses and loss expenses	0	0
Policy benefits	0	0
Policy acquisition costs and administrative expenses	14	36
Interest (income) expense	221	215
Other (income) expense	15	10
Amortization of purchased intangibles	0	0
Chubb integration expenses	49	137
Income tax expense	(112)	(150)
Net income	504	262
Comprehensive income (loss)	791	1,056
Other Chubb Limited Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net premiums written	6,710	5,995
Net premiums earned	6,772	6,597
Net investment income	742	669
Equity in earnings of subsidiaries	0	0
Net realized gains (losses) including OTTI	6	(394)
Losses and loss expenses	3,789	3,674
Policy benefits	168	126
Policy acquisition costs and administrative expenses	2,041	2,132
Interest (income) expense	17	11
Other (income) expense	(79)	27
Amortization of purchased intangibles	64	7
Chubb integration expenses	62	8
Income tax expense	234	268
Net income	1,224	619
Comprehensive income (loss)	$ 1,538	$ 1,721