Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2011		Dec. 31, 2010		Sep. 30, 2010		Dec. 31, 2009
Condensed Financial Statements Captions [Line Items]
Investments	$ 55,499		$ 51,407
Cash	766	[1]	772	[1]	487	[1]	669	[1]
Insurance and reinsurance balances receivable	5,403		4,233
Reinsurance recoverable on losses and loss expenses	12,837		12,871
Reinsurance recoverable on policy benefits	248		281
Value of business acquired	757		634
Goodwill and other intangible assets	4,817		4,664
Other assets	8,393		8,493
Total assets	88,720		83,355
Unpaid losses and loss expenses	38,476		37,391
Unearned premiums	6,594		6,330
Future policy benefits	4,376		3,106
Short-term debt	1,250		1,300
Long-term debt	3,360		3,358
Trust preferred securities	309		309
Other liabilities	10,605		8,587
Total liabilities	64,970		60,381
Total shareholders' equity	23,750		22,974		22,845
Total liabilities and shareholders' equity	88,720		83,355
Parent guarantor ownership percentage of subsidiary issuer	100.00%
ACE Limited (Parent Guarantor) [Member]
Condensed Financial Statements Captions [Line Items]
Investments	38		47
Cash	(70)	[1]	308	[1]	(26)	[1]	(1)	[1]
Investments in subsidiaries	23,302		22,529
Due from (to) subsidiaries and affiliates, net	664		564
Other assets	6		14
Total assets	23,940		23,462
Short-term debt			300
Other liabilities	190		188
Total liabilities	190		488
Total shareholders' equity	23,750		22,974
Total liabilities and shareholders' equity	23,940		23,462
ACE INA Holdings Inc. (Subsidiary Issuer) [Member]
Condensed Financial Statements Captions [Line Items]
Investments	29,160		26,718
Cash	640	[1]	573	[1]	284	[1]	400	[1]
Insurance and reinsurance balances receivable	4,883		3,710
Reinsurance recoverable on losses and loss expenses	17,530		16,877
Reinsurance recoverable on policy benefits	952		959
Value of business acquired	757		634
Goodwill and other intangible assets	4,264		4,113
Other assets	7,023		7,045
Total assets	65,209		60,629
Unpaid losses and loss expenses	31,696		30,430
Unearned premiums	5,560		5,379
Future policy benefits	3,759		2,495
Due to subsidiaries and affiliates, net	581		555
Short-term debt	850		1,000
Long-term debt	3,360		3,358
Trust preferred securities	309		309
Other liabilities	8,429		7,394
Total liabilities	54,544		50,920
Total shareholders' equity	10,665		9,709
Total liabilities and shareholders' equity	65,209		60,629
Other ACE Limited Subsidiaries And Eliminations [Member]
Condensed Financial Statements Captions [Line Items]
Investments	26,301	[2]	24,642	[2]
Cash	196	[1],[2]	(109)	[1],[2]	229	[1],[2]	270	[1],[2]
Insurance and reinsurance balances receivable	520	[2]	523	[2]
Reinsurance recoverable on losses and loss expenses	(4,693)	[2]	(4,006)	[2]
Reinsurance recoverable on policy benefits	(704)	[2]	(678)	[2]
Goodwill and other intangible assets	553	[2]	551	[2]
Other assets	1,364	[2]	1,434	[2]
Total assets	23,537	[2]	22,357	[2]
Unpaid losses and loss expenses	6,780	[2]	6,961	[2]
Unearned premiums	1,034	[2]	951	[2]
Future policy benefits	617	[2]	611	[2]
Due to subsidiaries and affiliates, net	83	[2]	9	[2]
Short-term debt	400	[2]
Other liabilities	1,986	[2]	1,005	[2]
Total liabilities	10,900	[2]	9,537	[2]
Total shareholders' equity	12,637	[2]	12,820	[2]
Total liabilities and shareholders' equity	23,537	[2]	22,357	[2]
Consolidating Adjustments [Member]
Condensed Financial Statements Captions [Line Items]
Cash						[1],[3]		[1],[3]
Investments in subsidiaries	(23,302)	[3]	(22,529)	[3]
Due from (to) subsidiaries and affiliates, net	(664)	[3]	(564)	[3]
Total assets	(23,966)	[3]	(23,093)	[3]
Due to subsidiaries and affiliates, net	(664)	[3]	(564)	[3]
Total liabilities	(664)	[3]	(564)	[3]
Total shareholders' equity	(23,302)	[3]	(22,529)	[3]
Total liabilities and shareholders' equity	$ (23,966)	[3]	$ (23,093)	[3]

[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, 2011, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

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

[3] Includes ACE Limited parent company eliminations.