Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Operations) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013		Jun. 30, 2014	Jun. 30, 2013
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	$ 4,559	$ 4,391		$ 8,744	$ 8,189
Net premiums earned	4,332	4,067		8,302	7,640
Net investment income	556	534		1,109	1,065
Net realized gains (losses) including OTTI	(73)	104		(177)	310
Losses and loss expenses	2,388	2,250		4,549	4,176
Policy benefits	144	110		258	241
Policy acquisition costs and administrative expenses	1,324	1,229		2,587	2,357
Interest (income) expense	72	73		143	133
Other (income) expense	(25)	37		(42)	27
Income tax expense (benefit)	133	115		226	237
Net income (loss)	779	891		1,513	1,844
Comprehensive income (loss)	1,348	(499)		2,456	217
ACE Limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net investment income	1	1		1	1
Equity in earnings of subsidiaries	745	842		1,447	1,756
Net realized gains (losses) including OTTI	0	0		0	12
Policy acquisition costs and administrative expenses	22	12		39	27
Interest (income) expense	(9)	(8)		(19)	(15)
Other (income) expense	(50)	(57)		(92)	(95)
Income tax expense (benefit)	4	5		7	8
Net income (loss)	779	891		1,513	1,844
Comprehensive income (loss)	1,348	(499)		2,456	217
ACE 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	1	1		1	2
Equity in earnings of subsidiaries	231	257		411	445
Net realized gains (losses) including OTTI	8	0		7	0
Losses and loss expenses	0	0		0	0
Policy benefits	0	0		0	0
Policy acquisition costs and administrative expenses	8	5		14	9
Interest (income) expense	70	69		141	131
Other (income) expense	6	6		20	15
Income tax expense (benefit)	(25)	(33)		(55)	(66)
Net income (loss)	181	211		299	358
Comprehensive income (loss)	511	(533)		777	(534)
Other ACE Limited Subsidiaries
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written	4,559	4,391		8,744	8,189
Net premiums earned	4,332	4,067		8,302	7,640
Net investment income	554	532		1,107	1,062
Net realized gains (losses) including OTTI	(81)	104		(184)	298
Losses and loss expenses	2,388	2,250		4,549	4,176
Policy benefits	144	110		258	241
Policy acquisition costs and administrative expenses	1,294	1,212		2,534	2,321
Interest (income) expense	11	12		21	17
Other (income) expense	19	88		30	107
Income tax expense (benefit)	154	143		274	295
Net income (loss)	795	888		1,559	1,843
Comprehensive income (loss)	1,364	(502)		2,502	216
Consolidating Adjustments and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Equity in earnings of subsidiaries	(976)	(1,099)		(1,858)	(2,201)
Net income (loss)	(976)	(1,099)		(1,858)	(2,201)
Comprehensive income (loss)	(1,875)	1,035		(3,279)	318
Scenario, Previously Reported [Member]
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written		4,391			8,189
Net premiums earned		4,067			7,640
Net investment income		534			1,065
Net realized gains (losses) including OTTI		104			310
Losses and loss expenses		2,250			4,176
Policy benefits		110			241
Policy acquisition costs and administrative expenses		1,229			2,357
Interest (income) expense		73			133
Other (income) expense		37			27
Income tax expense (benefit)		115			237
Net income (loss)		891			1,844
Comprehensive income (loss)		(499)			217
Scenario, Previously Reported [Member] | ACE Limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net investment income		1			1
Equity in earnings of subsidiaries		842			1,756
Net realized gains (losses) including OTTI		0			12
Policy acquisition costs and administrative expenses		12			27
Interest (income) expense		(8)			(15)
Other (income) expense		(57)			(95)
Income tax expense (benefit)		5			8
Net income (loss)		891			1,844
Comprehensive income (loss)		(499)			217
Scenario, Previously Reported [Member] | ACE INA Holdings Inc (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written		2,502			4,584
Net premiums earned		2,331			4,337
Net investment income		254			502
Equity in earnings of subsidiaries		0			0
Net realized gains (losses) including OTTI		28			38
Losses and loss expenses		1,434			2,687
Policy benefits		63			144
Policy acquisition costs and administrative expenses		674			1,300
Interest (income) expense		74			141
Other (income) expense		65			99
Income tax expense (benefit)		92			148
Net income (loss)		211			358
Comprehensive income (loss)		(533)			(534)
Scenario, Previously Reported [Member] | Other ACE Limited Subsidiaries
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net premiums written		1,889	[1]		3,605	[1]
Net premiums earned		1,736	[1]		3,303	[1]
Net investment income		279	[1]		562	[1]
Net realized gains (losses) including OTTI		76	[1]		260	[1]
Losses and loss expenses		816	[1]		1,489	[1]
Policy benefits		47	[1]		97	[1]
Policy acquisition costs and administrative expenses		543	[1]		1,030	[1]
Interest (income) expense		7	[1]		7	[1]
Other (income) expense		29	[1]		23	[1]
Income tax expense (benefit)		18	[1]		81	[1]
Net income (loss)		631	[1]		1,398	[1]
Comprehensive income (loss)		1,375	[1]		2,290	[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		(842)	[2]		(1,756)	[2]
Net income (loss)		(842)	[2]		(1,756)	[2]
Comprehensive income (loss)		$ (842)	[2]		$ (1,756)	[2]

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

[2] (2) Includes ACE Limited parent company eliminations.