Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011
Cash flows from operating activities
Net income	$ 1,301		$ 844
Adjustments to reconcile net income to net cash flows from operating activities
Net realized (gains) losses	134		118
Amortization of premiums/discounts on fixed maturities	103		63
Deferred income taxes	1		45
Unpaid losses and loss expenses	(644)		1,001
Unearned premiums	780		478
Future policy benefits	54		37
Insurance and reinsurance balances payable	(60)		449
Accounts payable, accrued expenses, and other liabilities	(9)		3
Income taxes payable			(91)
Insurance and reinsurance balances receivable	(551)		(578)
Reinsurance recoverable on losses and loss expenses	626		(296)
Reinsurance recoverable on policy benefits	48		29
Deferred policy acquisition costs	(159)		(137)
Prepaid reinsurance premiums	(283)		(156)
Other	42		254
Net cash flows from operating activities	1,383		2,063
Cash flows from investing activities
Purchases of fixed maturities available for sale	(11,522)		(13,041)
Purchases of to be announced mortgage-backed securities	(165)		(642)
Purchases of fixed maturities held to maturity	(136)		(234)
Purchases of equity securities	(93)		(170)
Sales of fixed maturities available for sale	7,840		9,346
Sales of to be announced mortgage-backed securities	192		639
Sales of equity securities	33		347
Maturities and redemptions of fixed maturities available for sale	2,280		1,758
Maturities and redemptions of fixed maturities held to maturity	739		656
Net derivative instruments settlements	(133)		(46)
Acquisition of subsidiaries (net of cash acquired of $95 in 2011)	(30)		(380)
Other	(255)		(132)
Net cash flows from (used for) investing activities	(1,250)		(1,899)
Cash flows from financing activities
Dividends paid on Common Shares	(318)		(223)
Common Shares repurchased	(11)		(68)
Proceeds from issuance of short-term debt	1,532		3,311
Repayment of short-term debt	(1,381)		(3,211)
Proceeds from share-based compensation plans	55		76
Net cash flows (used for) from financing activities	(123)		(115)
Effect of foreign currency rate changes on cash and cash equivalents	(7)		12
Net increase in cash	3		61
Cash - beginning of period	614		772	[1]
Cash - end of period	617	[2],[3]	833	[1]
Supplemental cash flow information
Taxes paid	259		265
Interest paid	$ 119		$ 112

[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 June 30, 2011 and December 31, 2010, 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 June 30, 2012, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[3] 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 June 30, 2012 one or more entities was negative; however, the overall Pool balances were positive.