Information provided in connection with outstanding debt of subsidiaries Balance Sheet (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2009
Assets (Condensed)
Investments	$ 55,189	$ 51,407
Cash	833	772	668	669
Insurance and reinsurance balances receivable	4,923	4,233
Reinsurance recoverables on losses and loss expenses	13,375	12,871
Reinsurance recoverable on policy benefits	250	281
Value of business acquired	796	634
Goodwill and other intangible assets	4,858	4,664
Other assets (condensed)	9,030	8,493
Total assets	89,254	83,355
Liabilities (Condensed)
Unpaid losses and loss expenses	38,951	37,391
Unearned premiums	6,913	6,330
Future policy benefits	4,384	3,106
Short-term debt	1,400	1,300
Long-term debt	3,360	3,358
Trust preferred securities	309	309
Other liabilities	9,824	8,587
Total liabilities	65,141	60,381
Shareholders' equity (FS)	24,113	22,974	21,410
Total liabilities and shareholders' equity	89,254	83,355
Subsidiary Debt Additional Disclosure (Abstract)
Parent guarantor ownership percentage of subsidiary issuer	100.00%
ACE Limited (Parent Guarantor) [Member]
Assets (Condensed)
Investments	40	47
Cash	(185)	308	30	(1)
Investments in subsidiaries	23,590	22,529
Due from (to) subsidiaries and affiliates, net	853	564
Other assets (condensed)	6	14
Total assets	24,304	23,462
Liabilities (Condensed)
Short-term debt		300
Other liabilities	191	188
Total liabilities	191	488
Shareholders' equity (FS)	24,113	22,974
Total liabilities and shareholders' equity	24,304	23,462
ACE INA Holdings Inc. (Subsidiary Issuer) [Member]
Assets (Condensed)
Investments	29,095	26,718
Cash	664	573	378	400
Insurance and reinsurance balances receivable	4,329	3,710
Reinsurance recoverables on losses and loss expenses	17,722	16,877
Reinsurance recoverable on policy benefits	941	959
Value of business acquired	796	634
Goodwill and other intangible assets	4,301	4,113
Due from (to) subsidiaries and affiliates, net		(555)
Other assets (condensed)	7,471	7,045
Total assets	65,319	60,074
Liabilities (Condensed)
Unpaid losses and loss expenses	31,820	30,430
Unearned premiums	5,820	5,379
Future policy benefits	3,767	2,495
Due to subsidiaries and affiliates, net	907
Short-term debt	1,000	1,000
Long-term debt	3,360	3,358
Trust preferred securities	309	309
Other liabilities	8,060	7,394
Total liabilities	55,043	50,365
Shareholders' equity (FS)	10,276	9,709
Total liabilities and shareholders' equity	65,319	60,074
Other ACE Limited Subsidiaries And Eliminations [Member]
Assets (Condensed)
Investments	26,054	24,642
Cash	354	(109)	260	270
Insurance and reinsurance balances receivable	594	523
Reinsurance recoverables on losses and loss expenses	(4,347)	(4,006)
Reinsurance recoverable on policy benefits	(691)	(678)
Goodwill and other intangible assets	557	551
Due from (to) subsidiaries and affiliates, net		555
Other assets (condensed)	1,553	1,434
Total assets	24,074	22,912
Liabilities (Condensed)
Unpaid losses and loss expenses	7,131	6,961
Unearned premiums	1,093	951
Future policy benefits	617	611
Due to subsidiaries and affiliates, net	(907)
Short-term debt	400
Other liabilities	1,573	1,005
Total liabilities	9,907	9,528
Shareholders' equity (FS)	14,167	13,384
Total liabilities and shareholders' equity	24,074	22,912
Consolidating Adjustments [Member]
Assets (Condensed)
Investments in subsidiaries	(23,590)	(22,529)
Due from (to) subsidiaries and affiliates, net	(853)	(564)
Total assets	(24,443)	(23,093)
Liabilities (Condensed)
Shareholders' equity (FS)	(24,443)	(23,093)
Total liabilities and shareholders' equity	$ (24,443)	$ (23,093)