Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Operations) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	$ 5,995	$ 4,076
Net premiums earned	6,597	3,927
Net investment income	674	551
Equity in earnings of subsidiaries	0	0
Net realized gains (losses) including OTTI	(394)	(89)
Losses and loss expenses	3,674	2,122
Policy benefits	126	142
Policy acquisition costs and administrative expenses	2,185	1,261
Interest (income) expense	146	68
Other (income) expense	28	(35)
Amortization of purchased intangibles	7	30
Chubb integration expenses	148	0
Income tax expense	124	120
Net income (loss)	439	681
Comprehensive income (loss)	1,541	642
Chubb Limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	0	0
Net premiums earned	0	0
Net investment income	1	1
Equity in earnings of subsidiaries	375	648
Net realized gains (losses) including OTTI	0	0
Losses and loss expenses	0	0
Policy benefits	0	0
Policy acquisition costs and administrative expenses	17	14
Interest (income) expense	(80)	(8)
Other (income) expense	(9)	(41)
Amortization of purchased intangibles	0	0
Chubb integration expenses	3
Income tax expense	6	3
Net income (loss)	439	681
Comprehensive income (loss)	1,541	642
Chubb INA Holdings Inc (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	0	0
Net premiums earned	0	0
Net investment income	4	1
Equity in earnings of subsidiaries	506	204
Net realized gains (losses) including OTTI	0	0
Losses and loss expenses	0	0
Policy benefits	0	0
Policy acquisition costs and administrative expenses	36	6
Interest (income) expense	215	69
Other (income) expense	10	(3)
Amortization of purchased intangibles	0	0
Chubb integration expenses	137
Income tax expense	(150)	(26)
Net income (loss)	262	159
Comprehensive income (loss)	1,056	24
Other Chubb Limited Subsidiaries
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	5,995	4,076
Net premiums earned	6,597	3,927
Net investment income	669	549
Equity in earnings of subsidiaries	0	0
Net realized gains (losses) including OTTI	(394)	(89)
Losses and loss expenses	3,674	2,122
Policy benefits	126	142
Policy acquisition costs and administrative expenses	2,132	1,241
Interest (income) expense	11	7
Other (income) expense	27	9
Amortization of purchased intangibles	7	30
Chubb integration expenses	8
Income tax expense	268	143
Net income (loss)	619	693
Comprehensive income (loss)	1,721	654
Consolidating Adjustments and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	0	0
Net premiums earned	0	0
Net investment income	0	0
Equity in earnings of subsidiaries	(881)	(852)
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
Income tax expense	0	0
Net income (loss)	(881)	(852)
Comprehensive income (loss)	$ (2,777)	$ (678)