Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities
Net income	$ 973	$ 250
Adjustments to reconcile net income to net cash flows from operating activities
Net realized (gains) losses	(260)	45
Amortization of premiums/discounts on fixed maturities	45	29
Deferred income taxes	(1)	18
Unpaid losses and loss expenses	(492)	1,016
Unearned premiums	265	125
Future policy benefits	27	(45)
Insurance and reinsurance balances payable	(126)	(47)
Accounts payable, accrued expenses, and other liabilities	(65)	(77)
Income taxes payable	41	32
Insurance and reinsurance balances receivable	(58)	230
Reinsurance recoverable on losses and loss expenses	422	(717)
Reinsurance recoverable on policy benefits	11	32
Deferred policy acquisition costs	(72)	(55)
Prepaid reinsurance premiums	(83)	7
Other	(55)	160
Net cash flows from operating activities	572	1,003
Cash flows from investing activities
Purchases of fixed maturities available for sale	(5,429)	(6,890)
Purchases of to be announced mortgage-backed securities	(54)	(343)
Purchases of fixed maturities held to maturity	(32)	(177)
Purchases of equity securities	(19)	(143)
Sales of fixed maturities available for sale	3,736	5,070
Sales of to be announced mortgage-backed securities	59	358
Sales of equity securities	26	317
Maturities and redemptions of fixed maturities available for sale	1,076	941
Maturities and redemptions of fixed maturities held to maturity	345	396
Net derivative instruments settlements	(195)	(85)
Acquisition of subsidiaries (net of cash acquired of $39 in 2011)	(25)	(45)
Other	(103)	(30)
Net cash flows used for investing activities	(615)	(631)
Cash flows from financing activities
Dividends paid on Common Shares	(159)	(112)
Common Shares repurchased	(11)	(68)
Proceeds from issuance of short-term debt	681	1,400
Repayment of short-term debt	(400)	(1,300)
Proceeds from share-based compensation plans	28	43
Net cash flows from (used for) financing activities	139	(37)
Effect of foreign currency rate changes on cash and cash equivalents	5	8
Net increase in cash	101	343
Cash - beginning of period	614	772	[1]
Cash - end of period	715	1,115	[1]
Supplemental cash flow information
Taxes paid	72	46
Interest paid	$ 37	$ 31

[1] ACE maintains two notional multi-currency 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 March 31, 2011 and December 31, 2010, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.