Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Operations) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	$ 4,185	$ 3,798
Net premiums earned	3,970	3,573
Net investment income	553	531
Net realized gains (losses) including OTTI	(104)	206
Losses and loss expenses	2,161	1,926
Policy benefits	114	131
Policy acquisition costs and administrative expenses	1,263	1,128
Interest (income) expense	71	60
Other (income) expense	(17)	(10)
Income tax expense (benefit)	93	122
Net income (loss)	734	953
Comprehensive income (loss)	1,108	716
ACE Limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net investment income	0	0
Equity in earnings of subsidiaries	702	914
Net realized gains (losses) including OTTI	0	12
Policy acquisition costs and administrative expenses	17	15
Interest (income) expense	(10)	(7)
Other (income) expense	(42)	(38)
Income tax expense (benefit)	3	3
Net income (loss)	734	953
Comprehensive income (loss)	1,108	716
ACE 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	0	1
Equity in earnings of subsidiaries	180	188
Net realized gains (losses) including OTTI	(1)	0
Losses and loss expenses	0	0
Policy benefits	0	0
Policy acquisition costs and administrative expenses	6	4
Interest (income) expense	71	62
Other (income) expense	14	9
Income tax expense (benefit)	(30)	(33)
Net income (loss)	118	147
Comprehensive income (loss)	266	(1)
Other ACE Limited Subsidiaries
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	4,185	3,798
Net premiums earned	3,970	3,573
Net investment income	553	530
Net realized gains (losses) including OTTI	(103)	194
Losses and loss expenses	2,161	1,926
Policy benefits	114	131
Policy acquisition costs and administrative expenses	1,240	1,109
Interest (income) expense	10	5
Other (income) expense	11	19
Income tax expense (benefit)	120	152
Net income (loss)	764	955
Comprehensive income (loss)	1,138	718
Consolidating Adjustments and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Equity in earnings of subsidiaries	(882)	(1,102)
Net income (loss)	(882)	(1,102)
Comprehensive income (loss)	(1,404)	(717)
Scenario, Previously Reported [Member]
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written		3,798
Net premiums earned		3,573
Net investment income		531
Net realized gains (losses) including OTTI		206
Losses and loss expenses		1,926
Policy benefits		131
Policy acquisition costs and administrative expenses		1,128
Interest (income) expense		60
Other (income) expense		(10)
Income tax expense (benefit)		122
Net income (loss)		953
Comprehensive income (loss)		716
Scenario, Previously Reported [Member] | ACE Limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net investment income		0
Equity in earnings of subsidiaries		914
Net realized gains (losses) including OTTI		12
Policy acquisition costs and administrative expenses		15
Interest (income) expense		(7)
Other (income) expense		(38)
Income tax expense (benefit)		3
Net income (loss)		953
Comprehensive income (loss)		716
Scenario, Previously Reported [Member] | ACE INA Holdings Inc (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written		2,082
Net premiums earned		2,006
Net investment income		248
Equity in earnings of subsidiaries		0
Net realized gains (losses) including OTTI		10
Losses and loss expenses		1,253
Policy benefits		81
Policy acquisition costs and administrative expenses		626
Interest (income) expense		67
Other (income) expense		34
Income tax expense (benefit)		56
Net income (loss)		147
Comprehensive income (loss)		(1)
Scenario, Previously Reported [Member] | Other ACE Limited Subsidiaries
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written		1,716	[1]
Net premiums earned		1,567	[1]
Net investment income		283	[1]
Net realized gains (losses) including OTTI		184	[1]
Losses and loss expenses		673	[1]
Policy benefits		50	[1]
Policy acquisition costs and administrative expenses		487	[1]
Interest (income) expense		0	[1]
Other (income) expense		(6)	[1]
Income tax expense (benefit)		63	[1]
Net income (loss)		767	[1]
Comprehensive income (loss)		915	[1]
Scenario, Previously Reported [Member] | Consolidating Adjustments and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Equity in earnings of subsidiaries		(914)	[2]
Net income (loss)		(914)	[2]
Comprehensive income (loss)		$ (914)	[2]

[1] Includes all other subsidiaries of ACE Limited and intercompany eliminations.

[2] Includes ACE Limited parent company eliminations.