Consolidated Statements Of Cash Flows (USD $) In Millions	9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010
Cash flows from operating activities
Net income (loss)	$ 835		$ 2,107
Adjustments to reconcile net income to net cash flows from operating activities
Net realized losses (gains)	878		(127)
Amortization of premiums/discounts on fixed maturities	105		103
Deferred income taxes	5		(16)
Unpaid losses and loss expenses	826		58
Unearned premiums	232		517
Future policy benefits	51		94
Insurance and reinsurance balances payable	158		(290)
Accounts payable, accrued expenses, and other liabilities	508		116
Income taxes payable	74		146
Insurance and reinsurance balances receivable	(1,103)		12
Reinsurance recoverable on losses and loss expenses	133		65
Reinsurance recoverable on policy benefits	26		12
Deferred policy acquisition costs	(154)		(172)
Prepaid reinsurance premiums	(52)		(167)
Other	476		317
Net cash flows from operating activities	2,998		2,775
Cash flows from investing activities
Purchases of fixed maturities available for sale	(18,783)		(22,762)
Purchases of to be announced mortgage-backed securities	(785)		(1,128)
Purchases of fixed maturities held to maturity	(285)		(514)
Purchases of equity securities	(289)		(336)
Sales of fixed maturities available for sale	13,567		17,233
Sales of to be announced mortgage-backed securities	756		1,063
Sales of equity securities	364		432
Maturities and redemptions of fixed maturities available for sale	2,603		2,666
Maturities and redemptions of fixed maturities held to maturity	966		931
Net derivative instruments settlements	67		11
Acquisition of subsidiaries (net of cash acquired of $81 in 2011)	(394)		(67)
Other	(317)		(197)
Net cash flows from (used for) investing activities	(2,530)		(2,668)
Cash flows from financing activities
Dividends paid on Common Shares	(342)		(323)
Common Shares repurchased	(168)
Proceeds from issuance of short term debt	3,985		175
Repayment of short-term debt	(4,035)		(175)
Proceeds from share-based compensation plans	82		41
Net cash flows used for financing activities	(478)		(282)
Effect of foreign currency rate changes on cash and cash equivalents	4		(7)
Net increase (decrease) in cash	(6)		(182)
Cash - beginning of period	772	[1]	669	[1]
Cash - end of period	766	[1]	487	[1]
Supplemental cash flow information
Taxes paid	306		296
Interest paid	$ 151		$ 130

[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.