Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013		Sep. 30, 2013		Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Investments	$ 63,254		$ 60,928
Cash	806	[1],[2]	579	[1],[3]	768	[4]	615	[4]
Insurance and reinsurance balances receivable	5,189		5,026
Reinsurance recoverable on losses and loss expenses	10,945		11,227
Reinsurance recoverable on policy benefits	228		218
Value of business acquired	491		536
Goodwill and other intangible assets	5,425		5,404
Other assets	11,219		10,592
Total assets	97,557		94,510
Unpaid losses and loss expenses	37,447		37,443
Unearned premiums	8,020		7,539
Future policy benefits	4,782		4,615
Short-term debt	1,851		1,901
Long-term debt	4,057		3,807
Trust preferred securities	309		309
Other liabilities	11,074		10,071
Total liabilities	67,540		65,685
Total shareholders' equity	30,017		28,825		28,218
Total liabilities and shareholders’ equity	97,557		94,510
ACE Limited (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Investments	31		32
Cash	8	[1],[2]	0	[1],[3]	11	[4]	103	[4]
Investments in subsidiaries	30,065		28,351
Due from subsidiaries and affiliates, net	768		844
Other assets	4		5
Total assets	30,876		29,232
Affiliated notional cash pooling programs	573	[2]	185	[3]
Trust preferred securities			0
Other liabilities	286		222
Total liabilities	859		407
Total shareholders' equity	30,017		28,825
Total liabilities and shareholders’ equity	30,876		29,232
ACE INA Holdings Inc (Subsidiary Issuer)
Condensed Financial Statements, Captions [Line Items]
Investments	25		10
Cash	12	[1],[2]	16	[1],[3]	165	[4]	2	[4]
Insurance and reinsurance balances receivable	0		0
Reinsurance recoverable on losses and loss expenses	0		0
Reinsurance recoverable on policy benefits	0		0
Value of business acquired	0		0
Goodwill and other intangible assets	0		0
Investments in subsidiaries	19,054		18,105
Other assets	272		258
Total assets	19,363		18,389
Unpaid losses and loss expenses	0		0
Unearned premiums	0		0
Future policy benefits	0		0
Due to subsidiaries and affiliates, net	556		714
Short-term debt	450		500
Affiliated notional cash pooling programs	32	[2]	0	[3]
Long-term debt	4,045		3,795
Trust preferred securities	309		309
Other liabilities	1,432		1,318
Total liabilities	6,824		6,636
Total shareholders' equity	12,539		11,753
Total liabilities and shareholders’ equity	19,363		18,389
Other ACE Limited Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Investments	63,198		60,886
Cash	1,391	[1],[2]	748	[1],[3]	1,464	[4]	859	[4]
Insurance and reinsurance balances receivable	6,149		5,835
Reinsurance recoverable on losses and loss expenses	19,948		20,057
Reinsurance recoverable on policy benefits	1,236		1,215
Value of business acquired	491		536
Goodwill and other intangible assets	5,425		5,404
Other assets	14,669		13,788
Total assets	112,507		108,469
Unpaid losses and loss expenses	46,003		45,714
Unearned premiums	9,828		9,242
Future policy benefits	5,790		5,612
Due to subsidiaries and affiliates, net	212		130
Short-term debt	1,401		1,401
Affiliated notional cash pooling programs	0	[2]	0	[3]
Long-term debt	12		12
Trust preferred securities			0
Other liabilities	12,681		11,655
Total liabilities	75,927		73,766
Total shareholders' equity	36,580		34,703
Total liabilities and shareholders’ equity	112,507		108,469
Consolidating Adjustments and Eliminations
Condensed Financial Statements, Captions [Line Items]
Investments	0		0
Cash	(605)	[1],[2]	(185)	[1],[3]	(872)	[4]	(349)	[4]
Insurance and reinsurance balances receivable	(960)		(809)
Reinsurance recoverable on losses and loss expenses	(9,003)		(8,830)
Reinsurance recoverable on policy benefits	(1,008)		(997)
Value of business acquired	0		0
Goodwill and other intangible assets	0		0
Investments in subsidiaries	(49,119)		(46,456)
Due from subsidiaries and affiliates, net	(768)		(844)
Other assets	(3,726)		(3,459)
Total assets	(65,189)		(61,580)
Unpaid losses and loss expenses	(8,556)		(8,271)
Unearned premiums	(1,808)		(1,703)
Future policy benefits	(1,008)		(997)
Due to subsidiaries and affiliates, net	(768)		(844)
Short-term debt	0		0
Affiliated notional cash pooling programs	(605)	[2]	(185)	[3]
Long-term debt			0
Trust preferred securities			0
Other liabilities	(3,325)		(3,124)
Total liabilities	(16,070)		(15,124)
Total shareholders' equity	(49,119)		(46,456)
Total liabilities and shareholders’ equity	$ (65,189)		$ (61,580)

[1] ACE maintains two notional multicurrency cash pools (Pools) with a third-party bank. Various ACE entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual ACE accounts are translated daily into a single currency and pooled on a notional basis. Individual ACE entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At September 30, 2014 and December 31, 2013, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[2] ACE maintains two notional multicurrency cash pools (Pools) with a third-party bank. Various ACE entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual ACE accounts are translated daily into a single currency and pooled on a notional basis. Individual ACE entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At September 30, 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[3] ACE maintains two notional multicurrency cash pools (Pools) with a third-party bank. Various ACE entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual ACE accounts are translated daily into a single currency and pooled on a notional basis. Individual ACE entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At December 31, 2013, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[4] ACE maintains two notional multicurrency cash pools (Pools) with a third-party bank. Various ACE entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual ACE accounts are translated daily into a single currency and pooled on a notional basis. Individual ACE entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At September 30, 2013 and December 31, 2012, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.